G0KYA's Amateur Radio Blog

UK propagation charts for January 2012

2012-01-03T08:20:00.000-08:00

Good solar conditions continue and we seem to have gone through quite a long period of settled geomagnetic conditions, which has helped no end.

The solar flux index has hovered around the 130 mark with no really large fluctuations and as a result we are still seeing the higher bands come to life, notably 10m.

But this is really the month for good low-band openings - 160m, 80m an 40m.

Tony G3ZRJ reported hearing long delay echoes on 80m at about 2100z on 1st January 2012. These are either signals coming around the world "the wrong way", or aided by magnetospheric ducting, or some other form of propagation that we don't really understand.

Whatever, it makes for some interesting effects. You can read more about one ham's views on LDEs here.

Just want to take this opportunity to wish you all a happy new year and remind you that you can still download a FREE guide to ionospheric propagation written by Alan Melia G3NYK and me.

Go to the January propagation charts from the UK

UK propagation charts for December 2011

2011-12-06T02:32:00.000-08:00

We are heading into the winter season now, but the conditions remain just as good. Don't be surprised if conditions to North America are not quite so hot on the higher bands in December - this is fairly normal as a comparison of the charts for October, November and December will show.

Propagation on 10m tends to close before the band has a chance to work west across the US.

The low bands (160m, 80m and 40m) come into their own with the longer hours of darkness so make sure you give them a look.

Go to December's UK short path propagation charts

Podcast: HF Propagation Report, Autumn 2011

2011-11-08T04:29:00.000-08:00

In this month's podcast I look at current solar conditions and how 10m is finally alive with signals - work the world with low power and simple antennas. If you don't do it now you could be missing out. Lasts about 6mins 30s.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

Titanic 100th anniversary next year - new book available

2011-11-03T06:33:00.000-07:00

Here's a good stocking filler.

Lawrence Beesley was a science teacher, journalist and author who was a survivor of the Titanic tragedy in 1912. In this dramatic real-life tale Beesley tells first hand what it was like to be on the Titanic as it plunged into the icy waters of the North Atlantic on that fateful night.

As well as describing the voyage, the collision with the iceberg and the subsequent sinking, Beesley documents what could have been done to save the 1,500 plus people who perished.

His account, and others, resulted in many changes to maritime law and procedure in an effort to make sure that a disaster of Titanic’s proportions should never happen again. “The loss of the S.S. Titanic – its story and its lessons” was first published in 1912, shortly after the disaster.

Now republished by InfoTech Communications, ahead of the 100th anniversary of the accident, the 116-page paperback book is available via Lulu.com, delivered straight to your door wherever you live in the world.

Find out more

UK propagation charts for November 2011

2011-11-01T05:18:00.000-07:00

The great conditions just keep on coming (bar any coronal mass ejections that is).

With sunspot numbers in the 120-130+ range, and autumnal conditions, there is plenty of DX to be had.

Keep on eye on 40m as Hawaii has been rolling in in the morning, often way past sunrise.

10m continues to be a great band, often open to the US and Caribbean in the afternoon. I especially like the KQ2H repeater in upstate New York on 29.620Mhz FM.

Go to November's UK short path propagation charts.

RSGB Convention updates

2011-10-10T01:26:00.000-07:00

A few updates for people who were at the RSGB Convention this weekend.

I have now updated the "Propagation to T32C" presentation to include the actual results we are seeing as at 9th October. There is a good fit with the predictions. Go to the T32C page
You can also download the Ionospheric Sounders presentation given at the Contest University
Carl K9LA talked about greyline propagation and mentioned my earlier research on the subject - you can read more here.

Steve G0KYA, 10th October 2011

UK propagation charts for October 2011

2011-10-04T12:19:00.001-07:00

This is what we have been waiting for. A high solar flux, autumnal conditions and DX rolling in. So get on the bands!

We have recently seen the solar flux index hit record highs for this cycle, but the sun has since calmed down a little. But with the SFI still being well over 100 we are seeing 10 metres open up to much of the world.

It is quite possible to work the USA this month on 10m, and at the same time you should be able to work the Far East, South America and even Australia (VK) at times. In fact, much of the world will be open to you when conditions are really hot.

There have also been some good openings to VK/ZL on 20m in the mornings too.

Don't forget to try and work the T32C Dxpedition to Kiribati in the Pacific. They are audible, but you'll need a good station or a good dose of luck and good propagation. Find out when and where to work them.

While this high solar activity is great, coronal mass ejections and solar flares will cause problems so keep an eye on the K index and GOES X-ray flux at www.solarham.com

Go to October's UK short path propagation charts.

Update: Working T32C

2011-10-03T11:45:00.000-07:00

The T32C Christmas Island DXpedition is well under way. They have now worked more than 300 stations in the UK. If you have a beam and a linear you are in with a chance. If you have a lesser station you might struggle a little bit.

You can read my original posting here, but for a quick overview of when and where to work them from the UK see the chart above (right click and save it to view it full size). I'm giving a talk on propagation to T32C at the RSGB Convention at the weekend.

New "CW only" ship's radio room clock

2011-09-13T01:00:00.000-07:00

For some time I have had a reproduction ship's radio room clock (and other items) for sale on Cafepress.com. You can read the full story about them here.

I have had a few enquiries from die-hard former ship's radio operators asking if they could have a "CW only" version.

These only had the red sectors at 15 mins and 45 min mins past the hour, when you had to go QRT and listen to 500kHz for emergency calls.

Well, I've now reworked the artwork and you can order the "500kHz" clock at "The Radio Room" on cafepress.com.

Podcast: HF Propagation Report, September 2011

2011-09-13T00:52:00.000-07:00

In this month's podcast I look at the effects of solar flares on the ionosphere - what they are, their effects, and how you can tell whether we have had one or not. Hint - the solar flux index and K index indicators won't help you! It lasts about 8mins.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

The W5GI “Mystery Antenna”

2011-09-06T12:40:00.000-07:00

W5GI's “Mystery Antenna” gets a lot of attention. Possibly because of its daft name.

It looks like a G5RV, but W5GI (now SK) used coax stubs to give what he called “a coaxial colinear array on 20m”. It consists of a half wave length (at 20m) of 300 Ohm ribbon that feeds a dipole centre.

Either side of the dipole centre are two pieces of wire 17ft long.These are then each connected to the inner of a 16ft 6in piece of RG58 coax. The outer is left unconnected. The far end of this is then shorted and connected to a further 17ft of wire, giving an antenna with a total span of 101ft.

I've now been using one for about three months, so find out what I think of it, is it really a "mystery" and is it worth making one!

Download the report.

Update: I have been doing some more modelling with the antenna as an inverted V and if mounted at about 10m with the ends at 3m you'll find that the lobes vanish and it becomes pretty omnidirectional at higher frequencies. On 20m you may find it radiates best broadside to the wire and less off the ends - this seems to match what I have found. Plots for 20m and 10m Inverted V have been added to the report.

UK propagation charts for September 2011

2011-09-03T01:46:00.000-07:00

Good autumnal condtions are coming. This is a good time for working north-south paths, such as UK to South Africa.

Also, keep an eye on 21MHz and higher. With the solar flux index above 100 we are seeing some nice openings - have worked Nigeria, and heard Thailand, Japan, China and the US West Coast over the past few days on 15m.

There have also been some good early morning (6.00-7.00 UTC) openings to Hawaii, the Pacific and the US west coast on 20m. Listen out for KH6s.

Even 40m is looking good - if you don't mind getting up early. It has been open to the Caribbean and most of the US at 4am UTC - I have to get up early on Fridays anyway to get an early train!

Have even heard WWZN Boston on 1510kHz medium wave on a 100ft W5GI dipole

Anyway, good DX and 73.

Go to the propagation charts

10m Slim Jim antenna

2011-08-31T08:56:00.000-07:00

I can't take much credit for this. The original 2m Slim Jim was designed by Fred Judd G2BCX, who lived in Norfolk before he became SK some years ago.

This 10m one, made from 450 Ohm slotted ribbon cable from Moonraker and secured on an 8m fishing pole, was inspired by Jim Bacon G3YLA (also a fellow Norfolk ham) who brought one along to our annual “Radio by the Seaside” event.

It worked so well (beating a Rybakov vertical by about 6 S points) that I thought it needed more attention.

The result is attached - it took a lot of fiddling to optimise the length, cut out and feedpoint, but now you don't need to!

Download the PDF construction information

Working T32C from the UK

2011-08-23T02:44:00.000-07:00

Update: Presentation download now includes comparison of predictions v actual as at 9th October.

The Five Star DXers Association are off to Christmas Island (Kiritimati) T32C in late September. If you want to work T32C it will pay to do a little bit of planning. In terms of the propagation to that part of the world there are a few factors we need to take into account.

The first question is “where is it?”. Kiritimati, or Christmas Island, is a Pacific Ocean atoll in the northern Line Islands - it should not be confused with an island of the same name in the Indian Ocean (VK9/X)!

The island lies 144 miles north of the the Equator and 8,400 miles from the UK

This highlights the first propagation problem – Kiritimati lies on a beam heading of about 335 degrees from the UK which puts our signals slap bang through the auroral oval around the north pole. Conversely, the long path heading of 156 degrees (and 16,400 miles) goes through the south auroral oval.

I have written a feature on propagation to T32C from the UK, which will appear in RadCom. I am also giving a talk on the subject at the RSGB Convention in early October.

In the meantime feel free to download a copy of the presentation, complete with notes, to get a feel for how hard (or easy) it is going to be.

Download the presentation in PDF format (1.4Mb)

Podcast: HF Propagation Report, August 2011

2011-08-11T06:22:00.000-07:00

A look at the last 30 days' solar and geomagnetic conditions and the link between sunspots and solar flares. Why you should use the smoothed sunspot number for prediction programs and how the Sporadic E season is coming to an end.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

UK propagation charts for August 2011

2011-08-02T00:25:00.000-07:00

Well, we are moving away from the summer solstice, but we are a long way from the better autumnal HF conditions that we should start to see in mid September.

The summer sporadic E season should also be diminishing too.

The last month or so has been characterised by big swings in the solar flux index and pretty poor conditions, although it doesn't pay to generalise. A chance glance at 17m a week or so ago showed a station from Los Angeles, calling CQ and with very few takers. He was about the only signal on the band!

These charts are based on a smoothed sunspot number of 45. The SSN is what is recommended by the originators of VOACAP and might seem a little low, but it is supposed to give better predictions.

Go to the propagation charts

The Wellbrook ALA330S active loop antenna

2011-07-12T05:15:00.001-07:00

I have had one of the above to test. It is a 1m aluminium loop with a built-in preamplifier and covers 3MHz-30MHz with reduced performance on lower frequencies.

I was particularly interested in how it performed on LF and Medium Wave. Connecting it up in the shack (it has a BNC connector on the loop and a separate power supply that feeds 12v to the loop) I was initially disappointed as it seemed noisy.

But this is because my house is just buzzing with electrical noise. Putting it outside, even leaning against a tree, made a massive difference.

I was able to receive BBC Radio Wales from here in Norfolk on 882kHz at about S6-7 on my Icom 756 Pro 3. This was a perfect copy and far better than I can get it on any of my other antennas, including a W5GI 100ft dipole and a Western HF10 dipole outside and an array of dipoles in the loft.

It was also able to hear a lot of other weak AM stations that were in the noise on my other antennas.

I also had a listen for some NDBs (beacons) and heard loads – CWL (Cranwell) on 423kHz, WBA (Wolverhampton) on 357kHz, WCO (Westcott) on 335kHz and WHF (?)on 332kHz. The strongest was NWI (my local airport in Norwich on 343kHz). These were all in daytime.

Turning to HF the loop heard everything that I could hear on my outside larger antennas. Sometimes a little noisier - but it is tiny.

Its nulling capabilities were excellent and a rotator would obviously be helpful.

If your interest is in LF/MF you might be better off with Wellbrook's ALA 1530 which offers 6dB better performance at the low-end of the band.

If you are only interesting in listening, but don't want to put up lengthy wires I can recommend the Wellbrook. I might test it on transatlantic MW DX this winter.

UK Propagation charts for July 2011

2011-07-07T09:40:00.000-07:00

This month's predictions are based on a smoothed sunspot number of 43. Expect to see fair openings up to 20, 17 and possible 15m.

The Sporadic E season is well under way too. Look for short skip on 15 and 10m.

Note: have just redone the charts with the revised Smoothed Sunspot Number of 43 - probably makes little difference.

Go to the charts

ARRL Field Day message via websdr.org

2011-06-25T10:31:00.000-07:00

Been playing with websdr.org today. This gives you access to remote SDR receivers all over the world.

I started by testing my antennas by listening for my signals at OE4XLC in Austria on 14MHz – this proved that my dipole works best on that path from the UK by about 10-13dB.

Its weird to hear your own signals coming back over the internet. I then remembered that K6KPH just north of San Francisco was going to be transmitting an ARRL Field Day message at 14:30UTC.

So I tuned in to the KC7IGT remote base in Renton,WA USA and listened on 40m. Low and behold there was the K6KPH CW signal and I recorded it.

I then played it back this is what it said. There are a few mistakes where fading or internet dropout meant I lost the signal, but you get the idea. Isn't this a great way to blend CW and new technology?

Give websdr.org a go yourself.

QST QST QST de K6KPH K6KPH K6KPH

SPCLCWVFOLLOWS SPCLECWVFOLLOWS

QST

DE W1AW5RSPCLC VFROM ARRL HQ NEWINGTON CT

JUNE 14 2011

TO ALL RADIO AMATEURS

FIELD DAY MAGIC COMES FROM VARIOUS SOURCES.

DURING THE SEASON OF E SKIP AND SPORADIC E OPERATORS CAN QUICKLY DISCOVER WHY 6 METRES IS CALLED THE MAGIC BAND

PROPAGATION ENHANCEMENTS HELP MAY E ARRL FICD PRIME TIME TO LEARN AND EXPERIMENT ON THE VHF/UHF BANDS.

EXPERIENCE THE WORLD ABOUT 50MHZ FOR YOURSELF.

ALL FIELD DAY GROUPS OPERATING IN CLASS AND THOSE AT 2F MANY UTILIZE A FREE VHF/UHF STATION WGHOUN INCREASING THEIR OPERATING CATEGORY.

QST DE K6KPH.

WORD FROM NASA OFFICIALS IS THERE IS A GOOD CHANCE THAT AT LEAST ONE, AND POSSIBLY BOTH, OF THE STATIONS ONBOARD THE ISS MAY BE PARTICIPATING IN FD THIS YEAR.

IT MAY TAKE EXTRA PLANNING AND BIT OF LUCK BY YOUR GROUP. BUT THERE IS NO GREATER BOOST OF ENTHUSIASM THAN TO COMPLETE A CONTACT WITH THE ISS.

LOOK TO THE HEAVENS AND SEE WHAT HAPPENS.

QST DE K6KPH 120C

THE QUALITY OF FIELD DAY IS DIRECTLY PROPORTIONAL TO THE AMOUNT OF FUN EXPERIENCED BY THE PARTICIPANTS.

LIFE IS MORE THAN JUST 140 CHARACTERS OR SHARING ONLINE. WHETHER YOU ARE AGE 8 0R 92.

USE THIS WEEKEND TO BE PART OF THE AMATEUR RADIO MAGIC THAT ARRL FIELD DAY OFFERS.

GOOD LUCK AND 73

AR GL DE K6KPH

UK Propagation charts for June 2011

2011-06-03T03:41:00.000-07:00

We’ve seen some massive swings in the solar flux index over the last few weeks, from around 80 up to 112. The authors of VOACAP (the basis for HamCap, which is used to produce the charts) always recommend that you use the smoothed or rolling average sunspot number for its predictions, which is what I always do. That’s why the charts are based on what can look like a low sunspot number when compared with reality.

The smoothed number is supposed to give the best overall result, although experience tells us that the actual conditions can vary dramatically from one day to another.

Conditions on 21MHz and higher will be dominated by Sporadic E (Es) events rather than F2 layer for the next couple of months, so expect to see short-skip openings on these bands (as well as 14MHz) even though the charts suggest that no propagation may be possible.

As always, keep an eye on solarcycle24.com to view the latest solar flux index (SFI) and K index, which may be a better short-term indicator of conditions as a raised K index will suggest CME and coronal hole activity that could adversely affect HF. Being logarithmic, a rise from a K index of one to four doesn’t sound like much, but certainly is.

As the K index is updated every three hours it is a good indicator. The non-logarithmic A index is an average of the last 24 hours so often doesn’t reflect events that have occurred in the last few hours.

Don't forget the free ebook on LF and HF propagation - see right.

Go to the UK HF propagation charts for June

10FM Repeaters in Europe

2011-05-23T23:56:00.000-07:00

With the summer Sporadic-E (Es) season here I have been reviewing a new 10m monoband rig for the RSGB's RadCom. It is an SS6900 from the French company CRT (although it is made in the Far East).

It is fully programmable, runs CW, AM, FM and SSB and works quite well, especially on 10FM.

I noticed that the list of 10m FM European repeaters at the HB9HD web site seemed to be out of date.

After a lot of searching I found an Excel spreadsheet that seems to be better and lists all the 10FM repeaters in this region. You can download it direct from http://lnx.arimi.it/.

Podcast: HF Propagation Report, May/June 2011

2011-05-17T01:30:00.000-07:00

A look at the last 30 days' solar and geomagnetic conditions and where have all the sunspots gone? What you can work on HF these months with a focus on Sporadic E.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

UK Propagation charts for May 2011

2011-05-15T06:46:00.000-07:00

This month's predictions are based on a smoothed sunspot number of 44. Expect to see good openings up to 20, 17 and possible 15m.

The Sporadic E season should be under way too from around 1st May. Look for short skip on 15 and 10m.

So good DX.

Anyway, here are the charts.

Video: GB0CMS, Caister Marconi Station

2011-05-05T11:57:00.000-07:00

I have produced a short video of my club's activities for International Marconi Day (IMD).

The Norfolk Amateur Radio Club ran GB0CMS - Caister Marconi Station - on the Norfolk coast as part of the international event.

The video explains what IMD is, tells you the history of the Caister station and takes you on a tour of the Lifeboat Visitor Centre.

It also looks at the equipment the club used to make 165 contacts in 24 countries on Saturday 30 April 2011.

See http://www.youtube.com/user/norfolkamateurradio

Podcast: HF Propagation Report, April 2011

2011-04-12T08:18:00.000-07:00

A look at the last 30 days' solar and geomagnetic conditions and how Solar Cycle 24 is humming . What you can work on each HF band and how to get a free ebook.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

Propagation predictions for International Marconi Day

2011-04-06T07:01:00.001-07:00

Right: Peter (M0RYB) hard at work on the key at GB0CMS last year.

International Marconi Day will be held on Saturday 30 April 2011 this year. I help to run GB0CMS at Caister Lifeboat in Norfolk and thought it would be a good idea to have some idea of propagation conditions to the other IMD stations around the world.

I have therefore created some charts that show the reliability of paths to Italy, East Coast of USA, West Coast USA, Iceland, Newfoundland and Uruguay - the locations of the majority of the IMD stations. These should help you get your award.

See http://www.infotechcomms.net/IMD/

For info, they were created using HamCap (a VOACAP-based program) using a smoothed sunspot number of 41 and based on 100W CW to a dipole at 35ft. Scale your results accordingly.

UK Propagation charts for April 2011

2011-04-04T04:27:00.000-07:00

This month's predictions are based on a smoothed sunspot number of 41. Expect to see good openings up to 15m, with 12m/10m making a good showing if the flux remains high. April is also good for North/South paths, such as UK<>South Africa/South America.

I would expect to see the Sporadic E season starting around 1st May too.

So good DX.

Anyway, here are the charts.

Podcast: HF Propagation Report, March 2011

2011-03-10T07:28:00.000-08:00

A look at the last 30 days' solar and geomagnetic conditions and how Solar Cycle 24 is really humming now. What you can work on HF with the right conditions.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

UK Propagation charts for March 2011

2011-02-28T12:08:00.000-08:00

I said last month that conditions had been dire - and then the flux rose up to 125. Yippee!

Unfortunately, there was flare activity as well, so the bands were up and down with good F2 layer openings, but then aurora as well. I expect conditions to be similar in March with big swings in the solar index as spots rotate into view and then disappear.

This month's predictions are based on a smoothed sunspot number of 39. Expect to see openings up to 15m, perhaps even 12m/10m if conditions continue to improve. March is also good for North/South paths, such as Uk<>South Africa. So good DX.

Anyway, here are the charts.

Ionospheric Sounding and Digisondes

2011-02-24T01:39:00.000-08:00

I recently gave a talk to my local club on ionospheric sounders (Digisondes). I will probably give the talk at the RSGB Convention in October 2011 as it seemed well received. While quite a complex subject, I have added some notes to the presentation to try and make it standalone.

The PDF explains what they are, what they show and how to use them. It also has links to free real-time digisonde plots from around the world and an historical database.

You can download the 4.1Mb PDF here.

Podcast: HF Propagation Report, February 2011

2011-02-09T03:53:00.000-08:00

A look at the last 30 days' solar and geomagnetic conditions, NASA's new prediction for Solar Cycle 24, a band-by-band breakdown and a short look at NASA's STEREO spacecraft.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

UK Propagation charts for February 2011

2011-02-01T04:24:00.001-08:00

I have now published my UK HF propagation charts for February 2011.

Regular readers will spot a small change - they are now colour coded. I never found the original charts very clear in terms of the reliability of the path, so I have now changed the software to show colour-coding for the reliability.

Don't get too excited as the colours go down to less than 25% reliability - if you are running a SteppIR at 120ft and a linear you might find paths like that opening up. For the rest of us look for reliability of 40-50% or more.

In case you hadn't noticed conditions have been dire for the last week or so - the solar flux is back down to 80-81 and openings on 21MHz and 28MHz are seemingly non-existent.

Or are they?

VP8ORK on South Orkney Island (take a look at map to see where it is - Falklands and head south) has been worked from the UK on both 21 and 28MHz so paths do open up, albeit weakly and not for very long.

Fingers crossed for some more sunspots. For a general overview of propagation conditions please refer to my posting for December/January. While we will move more towards equinox conditions later in the month I think what I said then still stands.

Scam warning

2011-01-19T08:58:00.000-08:00

I am getting an increasing number of enquiries from people who are either buying or selling amateur equipment. Someone is using my name and callsign to scam people. It isn't just me - there are lots of examples of this now.

The scam is that the seller wants you to send money via Western Union, or will send a cheque (which subsequently bounces). Their English is usually quite poor and, strangely, I don't live in Nigeria!

If you are approached by someone purporting to be me please put a comment on this blog entry. I'm not selling/buying anything at this time.

Steve G0KYA

HF Propagation – December/January

2010-12-17T06:05:00.000-08:00

G0KYA's propagation charts from UK for January 2011

This is the period when the low bands (160m, 80m and 40m) come into their own. The last two winters have seen great low-band propagation, with stations in the USA and Caribbean being worked on 80m well after sunrise. If you do nothing else keep an eye on 160m, 80m and 40m this winter as the relatively low levels of solar activity, the long winter nights and low D layer absorption means that DX may be heard all night long.

Band by band:

On 160m (1.8MHz or Top Band), solar absorption will prevent skip during the daylight hours. You should be able to work other UK stations out to about 50-80 miles via ground wave. The band will open around sunset and openings up to around 1,300 miles should be possible, with frequent openings up 2,300 miles. DX openings to the east from the UK should be possible around midnight and to the west before sunrise for well-equipped stations.

On 80m (3.5MHz), expect a similar pattern to Top Band with DX openings at night with peaks at midnight and around sunrise (greyline openings). Openings around the UK and out to around 500 miles should be possible during the day and between 750-2,300 miles at night. A low, horizontal antenna will be useful for relatively local, NVIS (Near Vertical Incidence Skywave) signals, but lower angle radiation, such as obtained with a vertical, will be required for DX.

Listen for DX from the West just before and just after sunrise – these are the months you are likely to hear US stations around 3795MHz in the morning.

40m (7MHz) is also another great DX band at this time of year. Forty metres should open to DX is an easterly direction during the late afternoon and towards the south at sunset. Paths during the afternoon may also include W6 (west coast USA) in mid winter. Openings to the west, including long path to VK/ZL should be possible after midnight and should peak just before sunrise. Relatively local contacts should be possible during the day, although low critical frequencies will mean that it is difficult to work other UK stations while perfectly possible to talk to European stations.

20m (14MHz) is likely to provide great DX openings during the hours of daylight. Peak conditions will be a couple of hours after sunrise for paths to the east and a couple of hours before sunset for paths to the west. Contacts up to 2,300 miles should be possible during daylight hours, but the band is likely to close to DX an hour or so after sunset. Occasional DX openings towards South America may be possible after nightfall.

17m/15m (18MHz/21MHz) should provide fairly good DX openings during daylight hours, although 15m may struggle to open at all on some days if the flux doesn’t rise above 80-90. The period from noon to late afternoon may be best, but both bands are likely to close at sunset and remain closed until some time after sunrise the following day.

12m/10m (24MHz/28MHz) may be good or bad depending on how the solar cycle progresses. If the flux stays in the 70s-80s there may be many days where there are no signals at all, although occasional brief openings to DX may be possible. If the solar flux heads towards the high 90s or more than 100 then good DX should be possible during daylight. A brief spell of sporadic-E can sometimes occur in the New Year resulting in very strong, but short-lived propagation on 10m out to around 1,300 miles.

A quick tip – if 28MHz seems dead listen to 27.555MHz USB which is a CB calling frequency. Activity there usually means that 10m may open up shortly after.

Stealth Antennas - now available in USA

2010-12-17T05:27:00.000-08:00

My RSGB book "Stealth Antennas" is now available in the USA from the ARRL.

Tiny postage stamp-size gardens, intolerant neighbours, planning permission problems, living in apartments: these are some of the challenges facing the modern radio amateur when trying to get on the air. Stealth Antennas offers clear practical advice to those who might have thought they were unable to put up a suitable antenna.

You can buy it in Europe from the RSGB and in the USA from ARRL.

I'd like to take this opportunity to thank the many US hams who helped with the book by contributing their stories.

The EFHW - a monoband end-fed half wave for 10m, 20m or any other HF band

2010-11-17T06:17:00.000-08:00

Update: Detailed construction details now available for download (PDF).

I like half wave dipoles. They are easy to make and easy to set up. They also perform very well and usually beat a compromise antenna hands down. With 10m about to come alive again as solar cycle 24 gets going what I wanted was a low-angle efficient radiator that could be put up and down in a couple of minutes.

My experience with ground plane verticals has been OK, but they are only as good as the earth beneath them. That is, they really need an extensive array of ground radials to work properly – not easy to put down when you are in a hurry.

I also like to use fibreglass fishing poles as antenna supports. These are available cheaply (I have a 7m version and a 10m version that I bought from Sandpiper at the Leicester rally). The only problem is that they don’t have lateral strength – they are good for supporting verticals, but not so good for half-wave horizontal dipoles.

What I really wanted to do was have a vertical half wave dipole, but the problem is that while the impedance at the centre of a dipole is about 50-75 Ohms, and very easy to match to coax, an end-fed half-wave has a very high impedance indeed, around 3000-4000 Ohms. If you just connect it to your coax or rig you will be disappointed.

Enter the End fed Half Wave as featured in my "Stealth Antennas" book - download the PDF for full details.

Update: Detailed construction details also now available for download (PDF).

NDBs (Non Directional Beacons) in the UK

2010-11-14T12:41:00.000-08:00

If you fancy a bit of LF DXing, these frequencies might be worth a try. They are non-directional beacons and are used by aircraft. I searched high and low until I found this list, so thought I would share it. Some may now be off the air.

I can hear my local NWI (Norwich) beacon but that's it. They send their idents in fairly slow Morse code. Have a listen, especially at night

Download the UK NDB list (PDF)

Understanding LF and HF Propagation ebook

2010-11-09T08:20:00.000-08:00

In 2008/2009 Alan Melia G3NYK and I wrote a series of features on understanding LF and HF propagation for the Radio Society of Great Britain's (RSGB) "RadCom" magazine.

My features consisted of a month-by-month look at each HF band in turn, showing the reader the propagation modes behind each band and explaining some of the technicalities of ionospheric propagation.

I looked at the D, E and F layers, Sporadic E, the MUF/LUF, using solar data, propagation programs, NVIS and much more.

Alan then took over and wrote three detailed features on LF propagation. We are told that the features were well received and as a result I have managed to persuade the RSGB to allow me to put them together into a single document, which is now freely available for amateurs worldwide to download.

I hope you enjoy it.

Steve G0KYA

Download the "Understanding LF and HF Propagation" PDF (1mb)

More on the 20m EH antenna

2010-10-13T04:58:00.001-07:00

I recently attended a lecture on small antennas at the RSGB convention by Professor Mike Underhill G3LHZ (pictured on the right with me). Mike asked me to take my 20m EH antenna along (which has been featured on this blog) so that he could take some measurements with his miniVNA.

I set it up on a tripod in the seminar room and hooked it up to my Yaesu FT-817. What surprised me (and the delegates) was the fact that it was receiving signals from around Europe at up to S9 +20dB.

OK, a dipole could have done the same, but for a four foot antenna mounted on a tripod indoors that's pretty good. The antenna was built for my RSGB "Stealth Antennas" book (available now from RSGB and on their website soon) and has now been put back in my loft, where it happily offers a 1.4:1 SWR and signals that get close to my other antennas, sometimes beating them.

Say that it works by Poynting Vector Synthesis (PVS) and the experts go mad. But think of it as a short, fat dipole with a matching network and it still does the same job and everyone is happy ;-)

As one delegate said: "My friend lives in a flat and would love one of these".

Click on my link to read more or see http://groups.yahoo.com/group/eh-antenna/

UPDATE: "Stealth Antennas" now for sale on RSGB website.

Podcast: HF Propagation Report, October 2010

2010-10-11T04:06:00.000-07:00

A change to the usual format this month. This Podcast features interviews with Dr Lucie Green, a solar physicist, who talks about her work on coronal mass ejections, and with Carl Luetzelschwab K9LA about what drives Top Band propagation and what to look for on 160m this winter.

Click on the headline to listen to the programme online or if you prefer to listen to it on your iPod search for G0KYA on iTunes.

HF Propagation Predictions, October 2010

2010-10-05T00:41:00.000-07:00

Note: You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

Solar conditions improved over the last month. As I write this on 5 October the solar flux is 76, but it did touch 91 during the last 30 days.

HF conditions have improved dramatically, but this is mainly due to the seasonal change. If you haven’t been on HF for the last few months get on now!

Openings have included 10m paths to Malaysia and VK, although I couldn’t hear them.

21MHz (15m) is opening up reliably – the US is easily workable at times. I worked W8FHF in Ohio using 100W to a long wire laying on the roof – he was stronger on that antenna than any of the others.

7MHz (40m) is also showing great promise. You can hear the US in the evening quite well and morning openings to VK are possible. Gerry VK7GK in Tasmania was 59 on 7.160MHz the other morning (long path) and gave me 57 on the Windom.

October also brings CQWW which always brings out the DX, so get on the bands.

Now lets look at the rest:

The equinox periods provide longer daytime periods than winter, but logically, shorter night-time periods too. These tend to be the best months for working North-South paths, such as UK to South Africa and South America.

On 160m (1.8MHz or Top Band), look for short-skip and DX openings at night. Again, no daylight skip is possible due to absorption, but openings out to 1,300 miles and occasionally further afield can be expected at night with conditions peaking around midnight and again at sunrise (greyline).

80m (3.5MHz) will generally follow the characteristics of Top Band at night, but will also provide good openings out to around 250 miles during the day. These will lengthen to around 500-2,300 miles at night with fairly good DX opportunities at times. At this point in the cycle 80m should still provide good DX as absorption is still quite low.

40m (7MHz) Forty metres should open to DX in an easterly direction at sunset. Openings to the west should be possible after midnight and should peak just before sunrise. Contacts should be possible during the day, although, again, lower critical frequencies may mean that it is difficult to work other UK stations while perfectly possible to talk to European stations. If the flux rises then 40m may open up to NVIS contacts around the UK. Look out for long path openings to VK/ZL in the morning too.

20m (14MHz) is likely to be the best DX band between sunrise and sunset. The bands may occasionally open after dark, perhaps to the south west form the UK. Good openings will be possible during daylight hours out to around 2,300 miles.

17m/15m (18MHz/21MHz) should provide fairly good DX openings during daylight hours, especially to Africa and South America, with 17m being open more often than 15m. Once again, 15m may struggle to open during times of low solar flux, but could provide good openings if it rises above about 80-90. Be prepared for some surprises though as this is a good month for 15m. Both bands are likely to close after sunset towards the end of the month, although do check for openings after dark as they can occur.

12m/10m (24MHz/28MHz) These could be disappointing bands if the solar flux remains low. If the solar flux heads towards the high 80s/90s then openings will occur on both bands, although 24MHz will open first. If it breaks the 100 mark then expect to see some good DX openings on 10m, especially in late autumn.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's HF propagation podcast on iTunes or at http://www.g0kya.blogspot.com/

Steve G0KYA
RSGB Propagation Studies Committee

New stealth antenna book released

2010-10-01T10:32:00.001-07:00

I’m pleased to announce that my new book “Stealth Antennas” was launched at the Newark Hamfest in the UK. The book is now available to buy from the RSGB .

It will also be available from the ARRL in due course.

It looks at a host of stealth antennas, including indoor dipoles, magnetic loops, stealth verticals, flagpoles, birdhouses and others. It also looks at more esoteric designs like the EH, Microverts, microloops, Isotrons, plus lots of case studies from around the world.

There are details on safety, minimising RFI, ununs, baluns, EFHW matching, the Rybakov – even a zig-zag portable dipole that fits in a folder.

Keep an eye open for it at rallies too.

UPDATE: Now for sale on the RSGB website.

Steve G0KYA

Propagation talk at Newark Hamfest, Oct 2010

2010-09-29T09:45:00.000-07:00

I will be giving a talk on HF propagation and prediction programs at the Newark Hamfest on Friday 1st October. I've made the presentation available as PDF file so that anyone who attends can download it. It may not make as much sense as it will with my commentary, but there is some useful info there. It is about 7Mb.

Click to download the presentation.

History of ships' radio room clocks

2010-09-17T09:10:00.000-07:00

Remember when all ships had real radio operators? If you do you'll know that the ops had to maintain "silent periods" when they wouldn't transmit, instead listening for distress calls on 500kHz and 2182kHz. For this they had a special radio room clock with sectors marked on it.

After the loss of the Titanic, the radio frequency of 500 kHz became an international calling and distress frequency for Morse code maritime communication. For most of its history, the international distress frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles [per second] or 500 kc.

2182kHz was added later and transmissions on 2182 kHz commonly use single-sideband modulation (SSB) (upper sideband only). However, amplitude modulation (AM) was often used in some parts of the world.

Maritime coastal stations used to maintain 24 hour watches on these frequencies, staffed by highly-skilled radio operators.

As a reminder, a ship's radio room clock would have the 500kHz silence periods marked by shading the sectors between h+15 to h+18 and h+45 to h+48 in RED. Similar sectors between h+00 to H+03 and h+30 to h+33 were marked in GREEN, which is the corresponding silence period for 2182 kHz.

Anyone breaking the rules would soon hear "QRT SP" in Morse Code, meaning "STOP SENDING - SILENT PERIOD!"

I've always wanted to have one of these clocks for my own shack, but couldn't find one. So … I decided to make one. I spent two days with a graphics program recreating a radio room clock from the Winthrop Clock Company of Boston, Ma., USA. It wasn't easy, but I then took the finished result, printed it and pulled apart a quartz clock that I bought for the job and installed it - what a lot of work!

The end result is shown in the photograph above and creates quite a lot of attention in my shack. It also keeps time really well too!

There is even The Radio Maritime Day each April where you have to obey the silent periods, so it comes in useful

Anyway, after all that work it seemed a shame to waste the artwork. I then found that I could upload it to a company called CafePress, letting people buy their own clock. While I was there I also designed some T-shirts, mugs, mouse mats and other goodies.

These products, including a reproduction radio room clock, let you relive those bygone, halcyon days when "sparks" ruled the maritime airwaves. So your shack can now look like a ship's radio room!

If you are in the UK go to http://www.cafepress.co.uk/theradioroom or if elsewhere http://www.cafepress.com/theradioroom – you can select the currency you wish to pay with.

I have one of the new Cafe Press clocks - it is about 10 inches in diameter and very striking. It is quartz powered so keeps good time and the tick isn't too loud either. Looks very nice on the wall and not too expensive either.

But remember QRT SP!

Podcast: HF Propagation Report, September 2010

2010-09-10T04:30:00.000-07:00

Report for September 2010 with a look at how solar cycle 24 still isn't going too well and why HF conditions will now start to improve in September and October. Just click on the Podcast headline above or search for G0KYA on iTunes.

HF Propagation, September 2010

2010-09-03T11:26:00.000-07:00

Note: You can find Steve's HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

Solar conditions still continue to be fairly poor. As I write this on 3 September there are sunspots, but the flux is stubbornly in the mid to high 70s. There have been auroral conditions over the past few days and we can expect to see more unsettled conditions as the cycle progresses.

Having said that, conditions are improving due to seasonal variations. We are heading away from the summer solstice and towards the equinox. The ionosphere is cooling down and its chemistry is changing. Traditionally late September and October are good times and we can expect to see increasing DX being worked.

In some respects this has already started to appear. There have been some good 20m openings from the UK to the West Coast of the USA and Alaska, plus openings to the Far East.

Given the lowish solar flux I think we will continue to see 20m (14MHz) and 17m (18MHz) as the “money bands”, but don't write off 15m (21MHz) which will open to DX, but perhaps not as often as the lower bands.

Late September will be the acid test – and with flux levels in the 70s we are unlikely to see many (any?) trans-Atlantic openings on 10m. Sorry - I would love to be proved wrong!

Now let's look at each band and what you can expect.

On 160m (1.8MHz or Top Band), look for short-skip and DX openings at night. Again, no daylight skip is possible due to absorption, but openings out to 1,300 miles and occasionally further afield can be expected at night with conditions peaking around midnight and again at sunrise (greyline).

80m (3.5MHz) will generally follow the characteristics of Top Band at night, but will also provide good openings out to around 250 miles during the day. These will lengthen to around 500-2,300 miles at night with fairly good DX opportunities at times. At this point in the cycle 80m should still provide good DX around midnight as absorption is still quite low.

40m (7MHz) Forty metres should open to DX in an easterly direction at sunset. Openings to the west should be possible after midnight and should peak just before sunrise. Contacts should be possible during the day, although lower critical frequencies may mean that it is difficult to work other UK stations while perfectly possible to talk to European stations. If the flux rises then 40m may open up to NVIS contacts around the UK.

20m (14MHz) is likely to be the best DX band between sunrise and sunset. The bands may occasionally open after dark, perhaps to the southern hemisphere. Good openings will be possible during daylight hours out to around 2,300 miles.

17m/15m (18MHz/21MHz) should provide fairly good DX openings during daylight hours, especially to Africa and South America, with 17m being open more often than 15m. Once again, 15m may struggle to open during times of low solar flux, but could provide good openings if it rises above about 90-100. Both bands are likely to close after sunset, at least later in the month..

12m/10m (24MHz/28MHz) These could be disappointing bands if the solar flux remains low. If the solar flux heads towards the high 80s/90s then openings will occur on both bands, although 24MHz will open first. If it breaks the 100 mark then expect to see some good DX openings on 10m, especially in late autumn.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's HF propagation podcast on iTunes or at http://www.g0kya.blogspot.com/

Steve G0KYA
RSGB Propagation Studies Committee

The Western HF-10 multiband dipole

2010-08-19T10:21:00.000-07:00

The Western HF-10 multiband dipole was born out of Fred Western M0BZI's attempts at working 80m from a small garden. His basic design starting point was the half size G5RV, to which he added inductors on each leg. Unhappy with the results, he then played around with the overall length and added a balun at the feedpoint.

The end result is the antenna as now supplied.

Specifications

The Western HF-10 is a 67 feet long dipole/doublet. It incorporates two loading coils placed towards the end of the legs and has a 15 foot 3 inch section of 450 Ohm windowed ribbon feeder to the centre feed point. At the end of the 450 Ohm feeder a ferrite rod balun is fitted for the transition to 50 Ohm coax. This appears to be wound as a 4:1 impedance transformer.

The build quality is excellent and all fittings are stainless steel. The balun housing is substantial and all crimped joints are very strong and designed so that they don't stress the antenna.

The antenna wire is Flexweave, which is both strong and easy to work with.

Installation

For the test I installed the antenna an an inverted V with the apex at about 30ft and the ends at about 10 feet.

Out of the box the antenna was found to be resonant at 3.7MHz.

Initial SWR tests were done using a 15ft length of RG58 coax to an MFJ analyser. Subsequently, a further 60ft of RG213 was added to bring the end into the shack. The subsequent SWR readings with the additional length of coax are shown in brackets.

SWR measured with MFJ 269 antenna analyser at end of 15ft RG58 coax (and at end of 60ft RG213 coax)

1.9: >31 (10.8:1)

3.5MHz: 3.7:1 (5.5:1)

3.7MHz: 1.2:1 (1:1) resonant point

3.8MHz: 4.3:1 (3.9:1)

7.0MHz: 6.2:1(3.3:1)

7.1MHz: 6.2:1 (3.3:1)

10.1MHz: 6.1:1 (3.2:1)

14MHz: 2.5:1 (1.6:1)

18.1MHz: 4.8:1 (2.7:1)

21MHz: 4.6:1 (2.3:1)

24.9MHz: 3.6:1(2.3:1)

28MHz: 1.2:1 (1.2:1)

29MHz: 1.9:1 (1.4:1)

50MHz 1.7:1 (1.5:1) – actually resonant at 48.6MHz

As can be seen, the SWR appears to go down once the additional coax is added. This is normal and is due to losses in the coax. Out of the box the antenna is naturally resonant on 80m, 20m and 10m.

The internal ATU on my Icom 756Pro 3 was able to find a 1:1 match on all bands 80m – 6m quite easily. Fred had said that his Yaesu FC-902 was also able to match the antenna on 160m, but the SWR was outside of the tuning range of my internal ATU.

Nevertheless, my external ATU was used to find a match on 160m, despite the antenna's short length.

First impressions

The antenna was mounted away from the house and fed via a 10 turn coax choke balun. This, plus the antenna's own balun resulted in a very quiet installation from a noise point of view.

With today's electrically noisy urban and suburban environments this was a breath of fresh air and made it that much easier to hear weak signals. The balanced design meant that there were NO detectable currents on the braid of the coax at all.

I had my doubts about the design of the antenna. It is very hard (if not impossible) to make a multi-band dipole that is coax fed and that will work on all bands. The Off Centre Fed Dipole (Windom or OCFD) is one design that gets close, but other designs (including the G5RV) fail to give a good match on all bands.

The problem is that they often display poor matches on many bands. The resultant poor SWR is often masked by coax losses on long runs, giving apparent better SWRs in the shack at the expense of losses in the coax caused by high SWR. This is why I did the initial SWR tests using a short length of coax.

Louis Varney G5RV himself also experimented with baluns at the open wire feeder/coax junction but abandoned the idea as the varying reactance at that point can lead to balun saturation and more losses/poor behaviour.

So I was interested to see how this model performed.

Performance

160m

I was able to tune the Western HF-10 on Top Band using an external ATU. The SWR is way too high for an internal ATU to match it on that band. Despite the antenna's short length I was able to work and hear UK stations, but signals were well down, typically around S5 compared with S9+10dB on my Windom (which itself is too short for Top Band). Nevertheless, if you only have room for a 67ft antenna it will let you experience the band. Noise levels were, once again, very low.

80m

The antenna's 80m performance was compared with an 85ft W3EDP and a 135ft home made OCFD (Windom) with a 4:1 balun, both with an apex at about 30 ft. I know exactly how these perform, having been using them in the RSGB's 80m Club Championship for three years. Best 80m DX on the OCFD has been VP8 Falkands and numerous US stations.

The antenna's noise level on 80m was found to be about three S points better than my existing antennas. This was because a) the Western HF-10 was situated further away from the house and b) it has an effective isolating balun. The offset nature of my OCFD means that it is prone to picking up noise on the feeder, despite a choke balun.

Signals from around the UK and Europe were generally found to be equal to or 1-2 S points down when received on the Western. This was to be expected as the antenna is only half the length of the Windom. The lower noise level however made it easier to hear people.

These results were fairly consistent – the difference was always between 0 and 10dB down. This isn't as bad as it sounds – signals that were S9 +20db on 80m might become S9 + 5-10dB. It was only very weak signals that were marginal. The low noise levels did make for easier listening though. I received a 59 +20db report from MJ0CTR in Jersey - what more could you ask for? At the time of testing (August) no 80m DX was heard.

40m (7MHz)

It was a similar story on 40m. EU signals were in general 1-2 S points down compared with the 136ft OCFD/85ft W3EDP, but lower noise levels made for easier listening. Some signals from DL were the same signal strength on all the antennas. Some were actually stronger on the Western.

30m (10MHz)

Again, lower noise was the order of the day. My OCFD is not really optimised for 30m and the Western outperformed it by up to 2 S points on CW around EU. A good antenna for this band.

20m (14MHz)

Signal strengths from Europe were roughly equal to the other antennas. This was apparent on many signals and was not a one-off. Some signals were stronger on the Western by up to 2 S points. Tests with stations in VO1 and VE9 on 14MHz showed the antenna outperformed my existing antennas. This was the case too with a short skip contact with Jon GM3JIJ on the Isle of Lewis. This antenna really shines on 20m.

17m (18MHz)

Signals were once again roughly equal to my OCFD, but sometimes up to 2 S points weaker than on a dedicated 17m dipole. Noise levels were once again better. Switching between the two you could see the effects of polarisation shifting in the ionosphere as one and then the other antenna became louder.

15m (21MHz)

My Windom does not really work on 21MHz. I normally switch to the W3EDP or use a 40m dipole. The Western outperformed both.

12m, 10m, 6m (21MHz, 24MHz, 28MHz and 50 MHz)

I managed to find a few Es signals on 10m a few days after i wrote the original text. They were all down about 2-3 S points on the Western compared with a dipole and the Windom.

General Coverage

I couldn't help but try the antenna out on the Broadcast Shortwave/Medium Wave bands. It was capable of picking up BBC Radio Wales from Washford in Somerset on 882kHz in daylight hours ( I live in Norfolk), although my other antennas were louder.

All of the stations I heard on the 7MHz, 9MHz, 11MHz, 15MHz were roughly all the same signal strength on both antennas. All India Radio on 6280kHz was down 20dB compared with my Windom.

Conclusions

I was very impressed with the Western HF-10. My first reaction was that it must be a bit of a compromise as it is only truly resonant on 80m. And yes, signal strengths were down a little overall. But the low noise characteristics of the antenna, and the fact that it could be persuaded to match on all bands 160 - 6m made it very usable.

On 20m the antenna matched or bettered my others in terms of performance, but with lower noise, which was a bonus.

You obviously trade off some performance on some bands compared with dedicated dipoles for each band, but this was never more than about 2 S points at worst (apart from Top Band). However, the low noise characteristics make up for this as I was often able to hear signals on the Western that were in the noise on my other antennas.

Given that these were also longer it shows how useful the Western HF-10 can be, especially if you do not have room for a full 80m antenna.

It also worked well on the shortwave broadcasts bands above about 4MHz.

For someone looking for an antenna that will fit in a small back garden, but will allow them to work all the HF bands, the Western HF-10 has a lot to offer.

Fred sells these antennas on Ebay or you can contact him via M0BZI@hotmail.co.uk

Night of nights, 13th July 2010

2010-07-13T00:12:00.000-07:00

Every year maritime stations in the USA commemorate (not celebrate!) the closing down of the use of Morse code for maritime traffic. This happens on 12th July each year, going on to 13th July in Europe and eastward.

Known as "Night of Nights" stations like KPH and KSM in California, plus WLO in Alabama transmit on the HF maritime bands, and some, like K6KPH, transmit on the amateur bands.

Being stupid, I thought I would set my alarm for 5am on the morning of the 13th July and see if I could hear anything - I wasn't very confident.

VOAProp suggested that 8MHz offered the best shot and as it turned out I heard KSM in Point Reyes, California on 8.438MHz, WLO in Mobile, Alabama on 8.658MHz and NMC in California on 8.574MHz.

I listened on 80m, 40m and 20m but heard nothing, other than a lone W station calling K6KPH on 40m.

KSM/ K6KPH broadcast regularly and can be heard in the UK, although they are always weak with me at this point in the solar cycle.

Its nice to hear CW being used on these bands again. You can find out more from the Maritime Historical Radio Society web site on http://www.radiomarine.org

HF Prediction Podcast, Summer 2010

2010-07-08T04:16:00.000-07:00

Report for Summer 2010 with a look at how the MUF stays high after dark, how to interpret sunspot numbers and how to use the solar wind indicator on solarcycle24.com. Just click on the headline above or search for G0KYA on iTunes.

HF Propagation and charts - July 2010

2010-07-01T09:39:00.000-07:00

Solar conditions continue to be fairly poor. As I write this on 1 July there is a solitary sunspot (number 1084) which has pushed the solar flux up to 75, but this is nothing special. Strong southward-Bz-pointing solar winds are also causing the K index to rise at times causing havoc.

The sunspot number is currently 11. This doesn't mean there are 11 sunspots – you get 10 for each group and one for each sunspot. So one sunspot in one group (naturally) leads to 10+1 =11.

Some people have suggested that the bands are improving, but I think they are confusing Sporadic E (Es) openings with F layer. This seasonal effect is opening up 20-10m and even 6m and 2m with good, strong openings up to 1,300 miles.

Multi-hop Es is stretching this even further, but we are not seeing an improvement in F layer propagation and Es will be less prevalent as the summer wears on.

Mid-to-late September will be the acid test – and with flux levels in the 70s we are not going to see many trans-Atlantic openings on 10m. Sorry!

In summer, Daytime MUFs are likely to be lower than those of winter. But night-time MUFs may be higher in summer than those in winter, so check 14MHz after dark for some nice surprises. Greyline around sunrise in summer can also be good – Peter M0RYB worked Hawaii on CW using a vertical half wave dipole for 20m that he is testing the other week.

Now let's look at each band and what you can expect.

On 160m (1.8MHz or Top Band), high levels of static and solar absorption mean that the band will not really support sky-wave contacts during the day. During darkness, short-skip openings may occur, but DX may be a rarity. Occasional openings can occur during the hours of darkness, especially around local midnight/early hours.

80m (3.5MHz) will generally follow the characteristics of Top Band with high levels of static, but will also provide good openings out to around 250 miles during the day. Absorption will grow to a maximum at midday for inter-G contacts. DX capabilities will be poor to fair during the hours of darkness.

40m (7MHz) will suffer from high static caused by high numbers of thunderstorms. Nevertheless, night-time openings should be reliable from sunset to sunrise. Local daytime openings will be possible on the whole. Night-time skip distances are likely to be between 500 and 2,300 miles.

20m (14MHz) is still likely to be the best DX band between sunrise and sunset, although the band will be noisier than the winter period and not as reliable for long-haul contacts. The higher MUFs at night mean that 20m may remain open during the evening to DX. Short skip may also be possible due to summer sporadic-E.

17m/15m (18MHz/21MHz) should provide a fair number of DX openings during daylight hours, especially to the southern hemisphere. Once again, 15m may struggle to open at times. Both bands are likely to close after sunset. Sporadic-E will provide good short-skip openings, predominantly in the May-June period.

12m/10m (24MHz/28MHz) are likely to be disappointing bands apart from Sporadic-E openings that will provide regular openings out to around 1,300 miles. Multi-hop sporadic-E openings are possible, providing relatively good, but short-lived paths to DX beyond this range. A typical multi-hop opening might provide brief contacts with the Middle East or USA, although they would be very hard to predict.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's HF propagation podcast on iTunes or at http://www.g0kya.blogspot.com/

Steve G0KYA

RSGB Propagation Studies Committee

HF Propagation, June 2010

2010-06-14T02:14:00.000-07:00

Solar conditions continue to be fairly rotten. In May we had a solar flux low of 69 and a high of …. wait for it …. 83. Hardly what we would expect for the rising part of the new cycle. It really needs to get over 100 if we are to see the higher bands open up to good F2 layer DX. Even then, we are going to have to wait until the Autumn.

But the good news is that the Sporadic E season is opening up the bands nicely, albeit for relatively short skip distances.

Look for very strong signals on 10m and 6m, which will suffer from heavy QSB. As the Es clouds move the countries you are able to work will change.

Peak times for Es are mid morning and mid to late afternoon, although look in the evening too.

Otherwise, Daytime MUFs are likely to be lower than those of winter. Night-time MUFs may be higher in summer than those in winter. Note that DX on the low bands, if possible, is unlikely to occur until around midnight or the early hours due to the late sunset.

But for now, let's look at each band and what you can expect.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's monthly HF propagation podcast on iTunes.

Steve G0KYA
RSGB Propagation Studies Committee

UK HF propagation charts, June 2010

2010-06-14T02:01:00.000-07:00

Later than usual as I've been working away, but here are the UK prop charts for June. Please note that these don't predict Sporadic-E conditions. These will give short skip on bands from 14-50MHz, with occasional openings on 2m too. The Es season appears to have been quite good this year, leading many people (falsely) to believe that solar cycle 24 is romping along. It isn't!

See www.infotechcomms.co.uk/propcharts

Moxon beam for 2m (144MHz)

2010-05-26T08:09:00.001-07:00

I was reading Practical Wireless the other day and found a piece about the PW 2m QRP contest on Sunday June 13 2010. I've never taken part in this, but thought that I might make the effort this year.

I have a Yaesu FT-817 and a couple of SLA batteries, but I haven't got a 2m beam. I used to own a 4el quad by Jaybeam which was brilliant, but sold it as I thought I would never use it again – duh! I looked at a few manufacturers' websites, but £50 for a 5el Yagi seemed a bit steep for one-day's operating.

So I decided to make my own. I wasn't interested in outright gain, but wanted something which was a) small and light, b) cheap and c) offered a little gain and some front to back.

The answer tuned out to be a Moxon rectangle beam. This is a two-element beam offering about 3dBd gain and massive 30dB front to back

If you head over to http://www.moxonantennaproject.com/wb5cxc/wb5cxc.htm you can find out all about it.

There is even a PC-based calculator that you can download.

So I headed off to B&Q and came back with 2m of white PVC trunking, two connector unions, and some PVC glue. I added some 2m PVC coated copper wire that I had, an S0239 socket and some 3.5mm heatshrink tubing – that's it. About £10 all in.

I modelled the beam for 145MHz and came up with the dimensions shown below. I then cut the PVC pipe accordingly and soldered/glued it all together. I used the heatshrink tubing to connect the ends of the elements. If I were making another one I would use a drinking straw first to strengthen them, although they seem OK with the tubing on its own.

Using my MFJ analyser I found that it resonated at about 136MHz – damn! I think this is because the velocity factor of PVC coated wire is about 94-95% and the computer simulation assumes bare wire.

So out came the junior hacksaw and I cut everything down to 94% of the original. This gave me a beam with about a 1:1.2 – 1:1.5 SWR across 2m. I fitted the beam to a 10m fishing pole (about 2m down from the top) using a couple of cable ties and hauled it up. I used 20m of Mini8 coax, but later that day found that it had a measured loss of about 2.4dB on 144MHz. Switching to RG213 reduced this to about 1dB.

So does it work? Yes, and quite well. I was able to hear the GB3VHF beacon at about S1-2 (148.20 km (92 miles) away). Swinging the beam around made the signal vanish into the noise. I could also hear the PI7CIS beacon in the Netherlands (JO22DC) - 221.11 km (137.4 miles). Swinging the beam vertically brought in repeaters from up to 60 miles away too. This was under flat conditions and I was unable to raise anyone on 144.300MHz SSB, more's the pity.

So for a total cost of about £10 a great little lightweight beam.

HF Propagation Podcast - May 2010

2010-05-07T09:29:00.000-07:00

Still very few sunspots at the moment, but lots of coronal hole activity! This month I also take a look at WinCap Wizard from Tabersoft. You can listen by clicking on the headline or search for G0KYA on iTunes.

HF Propagation report, May 2010

2010-04-30T02:12:00.001-07:00

Solar conditions have not been very good in the last month. In fact we had a run of about 12 days without a single sunspot. With the solar flux hovering around 74 it was like a return to the minimum once again.

Solar flare activity has been low, but even a small change in the Interplanetary Magnetic Field (Bz) swinging south was enough to cause the HF bands to misbehave.

This was characterised during the International Marconi Day event on 26 April. The morning was not too bad with DX from the Caribbean and VK being workable on 20m in the mid morning. By afternoon is was EU only.

May 1 should see the start of the Sporadic E season. This is characterised by very strong signals in the 14-50MHz bands, with very occasional openings on 2m.

Look for very strong signals on 10m and 6m, which will suffer from heavy QSB. As the Es clouds move the countries you are able to work will change.

Peak times for Es are mid morning and mid to late afternoon, although look in the evening too.

Daytime MUFs are likely to be lower than those of winter. Older books suggest this is due to the ionosphere heating up with resultant lower ion densities. But other theories suggest that this is due to a change in ionospheric chemistry between winter and summer.

The so-called “Seasonal Anomaly” is now thought to be due to a large summer electron loss rate caused by an increase in the molecular/atomic composition of the ionosphere and the reaction rates being temperature sensitive.

It is not all bad news though. Night-time MUFs may be higher in summer than those in winter. Note that DX on the low bands, if possible, is unlikely to occur until around midnight or the early hours due to the late sunset.

So let's look at each band and what you can expect.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's monthly HF propagation podcast on iTunes or at http://www.g0kya.blogspot.com/

Steve G0KYA
RSGB Propagation Studies Committee

UK HF propagation charts, May 2010

2010-04-30T01:49:00.000-07:00

My HF Propagation maps for May 2010 have now been published. Please note that these don't predict Sporadic-E conditions, which should start around the 1st May. These will give short skip on bands from 14-50MHz, wtih occasional openings on 2m too.

If you monitor 28 or 50MHz you'll hear stations from around southern Europe and into Scandinavia. Signals will be strong, but with heavy QSB. They may be fleeting as the Es clouds move. Peak times will be mid morning and late afternoon, but could occur any time, including evening.

See www.infotechcomms.co.uk/propcharts

HF Propagation Podcast - April 2010

2010-04-08T04:57:00.000-07:00

Few sunspots at the moment, but lots of solar flare activity - boo! Find out more and also hear about the origins of Sporadic E in this month's Podcast. You can listen by clicking on the headline or search for G0KYA on iTunes.

HF Propagation report - April 2010

2010-04-07T01:27:00.000-07:00

As the new cycle progresses we are starting to see more solar flare activity which is bringing aurora with it.

Over the past month we had a solar flux low of 76 and a high of 92 (on 13^th March). But we've also had some serious solar flares. We had a geomagnetic A index low of 1 on two occasions and a high of 28 in the first week of April.

In fact, the A index was still climbing as I wrote this and Auroral conditions were being recorded on 6m and 2m

We are still in the equinox period as far as HF propagation goes. These tend to be the best months for working North-South paths, such as UK to South Africa.

So let's look at each band and what you can expect.

On 160m (1.8MHz or Top Band), look for short-skip and DX openings at night. Little daylight skip will be possible due to absorption, but openings out to 1,300 miles and occasionally further afield can be expected at night with conditions peaking around midnight and again at sunrise (greyline).

80m (3.5MHz) will generally follow the characteristics of Top Band at night, but will also provide good openings out to around 250-300 miles during the day. These will lengthen to around 500-2,300 miles at night with fairly good DX opportunities at times.

17m/15m (18MHz/21MHz) should provide fairly good DX openings during daylight hours, especially to Africa and South America, with 17m being open more often than 15m. If we get more sunspots 15m will become a great DX band, as it did at times in February. Both bands are likely to close after sunset.

You can find HF short-path propagation prediction charts from the UK at:

http://www.infotechcomms.net/propcharts/

You can also listen to Steve G0KYA's monthly HF propagation podcast on iTunes or at http://www.g0kya.blogspot.com/

Steve G0KYA
RSGB Propagation Studies Committee

Propagation charts for April 2010

2010-04-02T23:22:00.000-07:00

I have just updated the propagation charts for April 2010 from the UK. The solar flux is actually quite low now and we are not seeing the rapid rise that you would expect at the beginning of the cycle. However, DX is out there, especially on North South paths. Expect to see Sporadic E starting up at the end of the month. Last year it was like a switch being thrown on 1 May.

We have Marine Radio Day on 10th April and International Marconi Day on 24 April. I have also done prop charts for the latter.

See http://www.infotechcomms.net/propcharts/

UK HF propagation charts, March 2010

2010-03-01T05:38:00.001-08:00

I've updated the short-path propagation prediction charts for March 2010. We should see some nice north-south paths on 21MHz if the solar flux comes up. We should also see 14MHz open to a lot of world.

See http://www.infotechcomms.net/propcharts/

G0KYA's HF Propagation Podcast for March 2010

2010-03-01T05:20:00.000-08:00

Solar Cycle 24 is under way, but we are not out of the woods yet. The last month has seen great DX openings when the flux hit the mid 90s, but now the sun is virtually spotless again.

Click on the headline link to listen to the Podcast or find it on iTunes.

MKARS 80 LSB QRP transceiver

2010-02-23T06:30:00.001-08:00

I have just finished my MKARS 80 LSB QRP transceiver kit - it took me about 10 weeks to complete on and off. The MKARS 80 is a kit from the Milton Keynes ARC and, while complex, can be built by anyone capable of reading and wielding a soldering iron. The slowest bit was cutting out the case and making the front panel.

I would like to say it worked first time, but it didn't. I wound the toroids incorrectly first off (read the instructions!) and had a short that I eventually fixed. Both builder error!

First QSO was with the homebrewers' net who said that it sounded great. I got 55-57/8 reports from around the UK using 5W and an 85ft end fed (W3EDP). If you are sharp eyed you will see that it says M6ELE on the box. This is my daughter's callsign and I thought it might encourage her to use it. I am using a cheap computer mic off Ebay, which came with two stones wrapped in Chinese newspaper inside for ballast! Maplin knobs as usual. The receiver is fantastic - I heard Japan when the board was just laying on the bench.

If you want more info see http://www.radio-kits.co.uk/mkars80page.html

I used Photoshop Elements to make front panel, which was then coated in plastic film and Spraymounted on. The case was sprayed with PlastiKote Velvet Touch - strange stuff , spray it when it is warm and keep about 40cm away. You end up with a stipple finish, but it is soft and marks easily.

Running Propagation Prediction Software on Mac OS X

2010-02-16T02:56:00.000-08:00

I use a Mac for most of my work - I still have a couple of PCs, but prefer the user experience with a Mac. I gave PCs up after running anti-virus software, registry cleaners et al on my Windows XP machines every other day, but that is another story.

I can run Windows XP using Parallels on my Mac, but it is memory intensive and slows down the machine, not to mention making the fan run solidly. Also, while running XP the clock gets out of sync very quickly, making the IBP beacon software useless within a minute or so.

So can you run programs like W6ELProp and VOAProp on a Mac in any other way. Well, yes you can.

Download Wine for Macs or Wineskin and you can run PC emulation. This doesn't appear to use up as many resources as full-blown Windows and works well.

I now have both W6ELProp and VOAProp running as and when I want them, and the clock stays perfectly synchronised.

You can get Wine for Macs at http://www.winehq.org/ or Wineskin at http://www.winehq.org/

If you are not aware VOAProp was written by Julian G4ILO and is a brilliant HF prediction program that uses the VOACAP engine. It also has a real-time graphical display of the IBP beacon network. W6ELProp is older and written by Sheldon Shallon. It uses a Fricker model of the ionosphere and is better than VOACAP at low band (80m ) predictions. It is getting clunky now, but is still very useful.

UK HF propagation charts, February 2010

2010-02-12T09:33:00.000-08:00

Here are the latest HF propagation charts for the UK. Propagation has improved dramatically. We are seeing the occasional opening on 10m (Israel today) and 15m has been open to the mid west and west coast of the USA. VE7 (Vancouver) has been booming in on 14MHz at local sunset.

These are based on 100W to a dipole at 35ft, with a smoothed sunspot number of 20. They are all short path too. You can try them here.

G0KYA's HF Propagation Podcast for February 2010

2010-02-12T08:19:00.000-08:00

HF prediction podcast for February 2010. More positive this month as Solar Cycle 24 gets under way. Also a quick look at www.solarcycle24.com - click on the heading to listen to the podcast.

Propagation charts for January 2010

2009-11-11T08:37:00.000-08:00

I have been experimenting with HamCap. It uses the VOACap engine to produce propagation maps and charts. As an experiment I have created a series of band-by-hour charts for the UK - now updaetd for January 2010.

These are based on 100W to a dipole at 35ft, with a smoothed sunspot number of 17. They are all short path too. You can try them here.

I think that 20m looks a bit optimistic with propagation way after sunset - time will tell!

G0KYA's HF Propagation Podcast for November 2009

2009-11-11T02:37:00.000-08:00

Will sunspot 1029 still be active when it comes back around the sun later this month? Will 10m open up again for CQWW CW like it did for CQWW SSB in late October? Find out more about this and the best HF bands to use in November in this month's podcast. Use the link above or search for G0KYA on iTunes.

Making sense of 10m propagation

2009-10-23T06:55:00.000-07:00

What's this? G stations working VK on 10m at sunspot minimum? Jordan and Thailand audible on 10m on a 65ft end fed?

That can't be right!

Well, it looks like it is. So why did 10m suddenly open up this week?

I think we need to look at a number of factors. First the solar flux was 72 so obviously no massive increase in solar UV output has caused it.

But it is October and this is a peak month for DX. The ionosphere in the Northern Hemisphere is cooling down, becoming more dense and the chemical composition changes too in the Winter compared with Summer, giving us a greater ion density.

To quote J K Hargreaves' “The Solar Terrestrial Environment”: You get an increase in NO concentration and a decrease ion loss rate due to the removal of water-cluster ions and a change in chemical reaction rates due to the temperature change.

In fact, if you feeling really awake read the whole 414 pages – I am sure the more I read the less I understand!

Anyway, so is that the whole story? No!

At the time of the openings the he Bz (Interplanetary Magnetic Field) was pointing south which means that solar wind was coupling with the earth's magnetic field and hot ions were pouring in.

Hence the 6m aurora the previous night – see www.solarcycle24.com.

The three-hourly K index reached 4 showing the effects of these ions on the earth's magnetic field.

So what we probably saw was a pre-auroral enhancement and that condx on the upper HF bands while good, are going to get worse. I'll let you know if I was right.

And they say that a high K index is bad for propagation – not always at the outset though.

Snowdonia Radio Company SRC X65 65ft end fed

2009-10-23T05:49:00.000-07:00

I bought one of these at a local rally. It is a 65ft wire and a 9:1 UN-UN. The guy who sells them is very friendly and is an ex Royal Signals op (I think). At only £30 it is barely worth making your own. I set it up as an inverted L with a 10m fishing pole. So it was about 9m up and about 10m sloping down to my shed, tied off with fishing line so that the end was about eight feet off the floor. I used a single ground stake and six 20ft radials.

Here are the results:
SWR measured with MFJ 269 at end of 30ft of coax.
Single earth stake and six 20ft radials

3.5MHz – SWR 3.5:1
3.6MHz – SWR 4.4:1
3.8MHZ – SWR 6.2:1
7.10MHz - SWR 4.8
10.1MHz – SWR 2.6:1
14.2MHz – SWR 2:1
18.14MHz – SWR 1.7:1
21.2MHz – SWR 1.9:1
24.9MHz – SWR 1.7:1
28.5MHz – SWR 1.3:1
29.6MHz – SWR 1.9:1
50.1MHz – SWR 1.9

On–air comparison with 135ft Windom (OCF)

80m
Similar signal strengths to Windom around UK, sometimes 2-4 S pts down, but 1-2 S pts. less noise. Holland down 2 S points. Germany 1 S pt better.

40m
Similar to Windom on PA and DL, F similar, IK similar, G similar.

20m
UA 1 S pt better on SRC, IK better by 1 S pt, YO similar

17m
Similar – inverted L has slight edge at times. Slightly quieter

15m
Better than Windom by about 1 S point, sometimes better, sometimes worse.

12m
All signals better by 1-2 S points

10m
Much better than Windom, dipole and mag loop, by about 2 S points. UA three S pts better. Slightly noisier. 5B4 beacon 2 S pts better.

I was very surprised at how good it was on 10m – or my Windom is very bad. I think this could be a keeper. See http://www.snowdonia-radio-company.co.uk/

Update: In the CQWW SSB contest on 24/25 October I worked more than 20 countries using the antenna on 10m, including ZS9 - very good!

HF Propagation Podcast, October 2009

2009-10-14T04:45:00.000-07:00

Slight change to the format this month. I was very pleased to meet Carl K9LA at the RSGB Convention last week. Carl is an HF propagation expert and a fellow member of the RSGB's Propagation Studies Committee.

I took the opportunity to talk with Carl about Solar Cycle 24. We also talked about the theory that galactic cosmic rays are affecting Top Band (160m) propagation during this solar minimum. You can listen to the podcast by clicking on the link above. Or you can search for G0KYA on iTunes.

What is WSPR?

2009-10-12T11:16:00.000-07:00

I gave a talk at the RSGB's National Convention on WSPR, what it is and how it is being used. I was asked if I could make the PowerPoint presentation available so here it is. It is quite a big download though - about 12Mb. Just click on the title to download it.

Propagation predictions for P29 DXpedition to Papua, New Guinea

2009-10-04T09:45:00.000-07:00

Gordon G3USR asked me to produce some propagation predictions for the P29 DXpedition to Papua, New Guinea, that he is joining between 20.10.09 – 10.11.09.

I have used a combination of ACE-HF and W6ELProp, plus a bet of guess work to come up with the attached. It will be interesting to see how they work out.

Click on the main heading to download the PDF

HF Propagation - Autumn

2009-09-16T10:50:00.000-07:00

40m (7MHz) Forty metres should open to DX in an easterly direction at sunset. Openings to the west should be possible after midnight and should peak just before sunrise. Contacts should be possible during the day, although, again, lower critical frequencies may mean that it is difficult to work other UK stations while perfectly possible to talk to European stations.

20m (14MHz) is likely to be the best DX band between sunrise and sunset. The bands may occasionally open after dark, mainly to the southern hemisphere. Good openings will be possible during daylight hours out to around 2,300 miles.

12m/10m (24MHz/28MHz) will continue to be disappointing bands at this point in the solar cycle. There may be many days where there are no signals at all, although occasional brief openings to DX may be possible, especially if the solar flux heads towards the high 80s/90s.

HF Propagation Podcast, September 2009

2009-09-16T04:33:00.000-07:00

Are sunspots disappearing completely? Some scientists think so. But a large spot is just around the back of the sun and should swing into view around September 20th. Find out more about this and the best HF bands to use in September in this month's podcast.

Also available on iTunes

HF Propagation Podcast, August 2009

2009-08-09T07:04:00.000-07:00

A look at HF propagation conditions for August 2009, including the solar and geomagnetic data for July 2009, Sporadic E and how to work stations VQ9JC on Chagos Island and 5N0OCH in Nigeria. All this plus a band-by-band round-up of what you can work and hear.

Also available on iTunes

A 2m Slim Jim made from 300 Ohm ribbon cable

2009-07-30T12:30:00.001-07:00

A project at my local club (Norfolk Amateur Radio Club) turned into a bit of a nightmare recently. The project was simple - let some of the youngsters make a 2m Slim Jim antenna out of 300 Ohm ribbon cable.

We had made plenty of these before and they work well. You cut a piece of white, translucent ribbon cable of about 60 inches long and bare the wires at both ends by about half an inch. You then twist the ends together and solder, giving you an overall length of 59 inches.

Then you cut a one-inch slot on one side about 18 inches up from the bottom. Feed it across the two elements about two inches from the bottom and there you go – except we didn't.

For this exercise we had bought some black, heavy duty 300 Ohm ribbon. When we made them up they came out on an MFJ analyser at about 136MHz – they were obviously too long.

After much messing around I decided that the only reason must be that the velocity factor of the black ribbon cable is different to the translucent stuff.

Out with a calculator and I reckoned it was about four inches too long. We decided to shorten one – carefully – until we got it right. We could then use it as a template for the rest.

We ended up with a length of 53 inches, with the slot 16 inches up from the bottom. This gave a virtual 1:1 – 1:1.5 SWR at 145MHz.

My prototype Slim Jim has now been put in a piece of white piping from the local hardware store with the silver top off a room spray on one end and the end off a toothpaste tube on the other.

It looks quite good and cost about £5 all in.

So if you are going to make a Slim Jim from ribbon cable do bear in mind that the length will depend on the type of cable you use.

HF Propagation Forecast June/July 2009

2009-07-30T07:22:00.000-07:00

Here is the latest HF Propagation Podcast for June/July 2009 as featured on "This Week in Amateur Radio". Solar activity remains very low with virtually no visible sunposts. The Summer (in the Northern Hemisphere) is characterised by lower MUFs during the day than in winter, but higher MUFs in the evening/night. 14MHz may stay open later in the evening than it does in Winter. Sporadic E conditions are excellent, giving good short-range openings on 14, 21, 28 and 50MHz, occasionally getting up to 144MHz.

Also available on iTunes

The Hustler 5-BTV

2009-07-03T10:38:00.000-07:00

I quite like the Hustler 5-BTV vertical. It is rugged, well made and gives you five bands in one antenna.

BUT - you must make sure you have a good earth radial system if ground mounted. Putting a single earth stake in will work, but it will be quite deaf. Adding radials makes a big difference. They don''t have to be resonant. As they are lying on the ground this detunes them anyway - just make sure that they are as long as the antenna is high.

In fact, there is no hard and fast rule about radial length, apart from more shorter ones are better than fewer longer ones.

The golden number to aim for is 120 radials, but that isn't really practical. As you add radials you will notice the SWR change and the performance improve, but as you add more the effect will be less - the law of diminishing returns. By the time you get to 48 -64 you probably won't see much difference.

In a test, I tried a 5BTV mounted on a single three foot ground stake - it was very, very deaf, although the SWR was fine. It was at least three S points down on a dipole and a Windom.

Adding just six 26ft radials made a big difference - it equalled the dipole and Windom and actually beat them at times.

A ground mounted vertical like a Hustler or Butternut is only half an antenna - put down a decent radial system and it will really improve.

See this feature on the DXEngineering website.

Are coax-fed G5RV's lossy?

2009-07-03T10:27:00.000-07:00

These were some tests I did with a G5RV mounted as an inverted V at about 25 feet and the ends at about six feet.

I first measured the coax losses of 30ft of RG58 with an MFJ 259 analyser, which were as follows:

3.6 MHz: (0.6db)

7.1 MHz (0.7db)

14 MHz (1.3db)

21.2 MHz (1.4db)

28.5MHz (1.8db)

I then took SWR readings on five bands - below are the SWR figures as measured at the bottom of the G5RV's ladder line with an MFJ 259 analyser. The figures in brackets are the SWR readings as measured in the shack after a run of 30ft of RG58.

Using the calculator at: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12232 the final figure is therefore the calculated total loss taking the measured loss and SWR loss into account.

3.5MHz: 2.0 (1.7) - 0.646dB

3.6MHz: 3.0 (2.2) – 0.724dB

3.8MHz: 4.2 (3.6) – 0.823dB

7.0MHz: 2.2(2.2) - 0.784dB

7.1MHz: 2.4 (2.3) – 0.806dB

14.150MHz: 4.5 (5.7) – 1.954dB

21MHz: 3.9 (9.6) – 2.83dB

28MHz: 3.6 (12.4) – 3.862dB

29MHz: 3.2 (9.5) – 3.397dB

As you can see the antenna was only really a good match at the bottom end of 80m and on 40m. The total loss gets worse as you go up in frequency. At 28MHz the combined loss was 3.8dB - you are losing half your power.

But the worst case scenario of 25ft+30ft of generic window line at an SWR of 12.4 on 28MHz is only 0.405dB.

So the conclusion is, a G5RV fed with RG58 coax is fine for 80m and 40m, but losses mount as you go higher in frequency. If you want to work the higher bands think about using open wire feeder all the way to the tuner. You then have a doublet with much lower losses.

Long wire and Un-Un part 2

2009-06-17T04:40:00.000-07:00

In the next round of tests I used the same 9:1 Un-Un wound using PVC covered cable and a T200-2 toroid. Note in the photograph that the PVC tape is only used to keep the turns neatly arranged.

If you want to build your own follow these instructions:

Building a 9:1 unun

To understand how to construct an unun lets build a 9:1 version. You will need a T-200 (red) toroid and three pieces of wire, each 24 inches (60cm) long . It will also help if you a small plastic box with an SO239 socket mounted at one end and with two wing nuts or mounting posts at the other. In the UK you can buy a small plastic box from Maplin which is watertight with a rubber seal, yet inexpensive.

It will help if the wires are different colours, although that isn't critical if you have a multimeter available. It just makes it a lot easier to follow these instructions.

For the sake of this explanation I'll assume that you are using green, red and black pieces of wire.

Put the three pieces of wire together and wind them carefully onto the T130-2 toroid. Place the wires (left to right) green-black-red, and wrap nine turns on to the toroid.

Try not to let the wires overlap.

You should end up with a toroid with three wires extending from the left winding and three wires extending from the right.

Now twist and solder the left black wire with the right red wire. This can be covered with PVC tape once complete.

Now twist the left green wire with the right black wire. Strip the ends of the two wires, twist and solder them together leaving the length about 2” long from the toroid.

Finally trim and strip the remaining right green wire and solder another 5” piece of green solid wire to it.

Now take the left green wire and right black wires that you twisted together and connect them to the centre pin of the SO239 socket – this is the input side and will connect to your radio via a length of coax.

One of the green wires is now soldered to the ground connection of the SO239 socket. The other end of the wire you soldered on (which is connected to it) becomes the earth connection for the unun and typically goes to a ground stake and ground radials.

This leaves the remaining red wire which connects to the other wingnut and will become the connection for the antenna.

If you are worried about the wires unravelling you can either use PVC tape to hold them in place or plastic cable ties.

So how do we use an unun? Lets look at a typical example.

This time I erected a 10m high fishing pole and attached a 65ft quarter wave antenna for 80m in an inverted L fashion. That is, 10m up and then 9.8m out to the nearby summerhouse.

This was arranged away from the house and fed with 12m of RG8 coax, a single earth stake and two 20ft radials at the feed point..

Here are the SWR readings at the end of the coax:
3.5MHz – SWR 3:1
3.65MHz – SWR 4.2
3.8MHz – SWR 5.9
7.10MHz - SWR 13.6:1
10.1MHz – SWR 2.5:1
14.2MHz – SWR 3.3:1
18.14MHz – SWR 1.8:1
21.2MHz – SWR 2.4:1
24.9MHz – SWR 1.9:1
28.5MHz – SWR 1.2:1

From this you can see that by shortening the wire to 65ft from the original 85ft you gain 80m, but lose 40m. The rig (FT2000) would quite happily tune seven bands with its internal ATU.

Here are the quick comparison results against my 80m Windom and parallel-fed dipoles in the loft for 40m, 20m, 17, and 10m.

80m
Not as good around the UK as the Windom - probably due to the maximum current being in the vertical section. Modelling shows the antenna to be down about 10dB on a low dipole.

30m
Lithuania similar. Other EU and Italy similar. Bulgaria down 2 S points

17m
Similar – inverted L has slight edge at times. Slightly noisier

15m
Better than Windom by about 1 S point.

10m
Much better than Windom, dipole and mag loop around Europe via Es, by about 2 S points. Slightly more noise (+ 1 S point).

From this I can see that I need to do more tests, especially on 20m, but for an all-in cost for the antenna of about £15-£20 it shows promise. If you have a tree then the up and out idea with a 65ft wire looks quite good. A way to get 40m back would be to put a 40m trap in the wire at the 10m mark.

If you don’t fancy making your own UnUn you can buy the whole antenna from the Snowdonia Radio Company for £35 inc P&P – see http://www.snowdonia-radio-company.co.uk/srcproducts.html

Long wire and Un-Un part 1

2009-06-17T04:04:00.001-07:00

I have been playing with a 4:1 unbalanced-unbalanced transformer and a long wire. The theory is that the Un-Un reduces the impedance at the feed point to a point that your internal ATU can cope with.

My first tests were with my 85ft end fed and were not too encouraging. These are the SWR results I got using an MFJ analyser:

1.9MHz >30
3.6MHz: 10
7.1MHz: 3.0
10.1Mhz: 5.7
14.150MHz: 2.4
18.1MHz: 2.9
21MHz: 2.6
24.93MHz: 2.0
28MHz: 5.7

from these you can see that the rig would be able to match the long wire on five bands. On test it would not match on 80m, although when run as a W3EDP through my external ATU it works well.

I then wound a 9:1 Un-Un (sometimes referred to as a magnetic long wire Balun) and tried again. Here are the results:

3.6MHz – SWR 28:1
7.10MHz - SWR 1.9:1
10.1MHz – SWR 3.6:1
14.2MHz – SWR 1.9:1
18.14MHz – SWR 3.8:1
21.2MHz – SWR 2.5:1
24.9MHz – SWR 3.5:1
28.5MHz – SWR 8.6:1

While 40, 20 and 15 metres were quite good I can't really recommend this as a multiband solution.

In all then, it is too long and not really worth playing with.

HF Propagation report - Summer

2009-06-17T03:53:00.000-07:00

Daytime MUFs are likely to be lower than those of winter due to changes in the ionosphere. But night-time MUFs may be higher than those in winter. Note that DX on the low bands, if possible, is unlikely to occur until around midnight or the early hours due to the late sunset. Absorption will be high of the HF bands, as will noise. In all, not the best of periods for HF.

World Radio - an online ham radio magazine

2009-06-08T12:03:00.000-07:00

They say that you can't get something for nothing, but that's not quite true. In this recession many magazines are struggling as advertisers look to their budgets.

The UK's "Monitoring Monthly" has folded, which is a great shame as it had some very interesting features. The editor Kevin Nice deserves a round of applause for having the guts to start the publication in the first place and I will miss it.

However, in the US someone has thought long and hard about this and has come up with the solution. If the biggest cost in a mazgazine is the print and distribution costs, why not make it an online publication - and make it free too!

The result is World Radio Online and do you know what? It is actually very good - and it doesn't cost a penny (or cent!)

Heres a sample from the current issue:

USHAGAT: - a Low Budget DXpedition to Alaska
VERTICAL TALES: Adding 17-Meters to a Hustler 6-BTV
FISTS CW Club: An 11-Year Old’s View of Amateur Radio
10-10 INTERNATIONAL: Investment Strategy
TRAIL-FRIENDLY RADIO: Plenty of ‘Enhanced’ Audio to Overcome Nature’s Soundtrack
PROPAGATION: Changes in the Earth’s Magnetic Field
AMATEUR SATELLITES: International Amateur Satellite News
AERIALS: Antenna Efficiency

Take a look. I guess the more people subscribe the more advertisers will back it.

Go to http://www.cq-amateur-radio.com and click on the WORLDRADIO link at the top left corner of the page.

President Lincoln 10m

2009-05-07T05:01:00.001-07:00

The President Lincoln has been around for years, but still makes a good little monoband rig for 10m.

I was first introduced to the range when I went to Florida on holiday and bought a Uniden HR2600 for about £50. This is a 10m-only rig with repeater shift and about 10w FM/25W SSB output and I loved it.

However, it didn’t get too much use in the sunspot minimum years and I decided to sell it – what an idiot!

Anyway, I have never been able to find another one to buy, so settled on the President Lincoln. There are loads of these on eBay for around £120 - £180.

The Lincoln covers 26-30MHz in eight bands. It is very similar to the HR2600 but doesn’t have repeater shift.

Unlike the Albrecht AE 485S I reviewed earlier it does have continuous 100, 10 and 1kHz tuning. You don’t get the memory feature of the Albrecht, but you do get a built-in SWR meter and a scan button. It also has an RIT, mic gain button and RF gain.

Switching to the ham band (28-29.7MHz) I was able to hear everything that my Yaesu FT-2000 could hear, including beacons in Italy, Slovenia and Norway. I worked a couple of stations on SSB and got 57 reports.

I had a bit of a problem with mine. After storing it in the loft for two years the tuning control was a bit odd – in some positions it was fine, in others it would either not change channel or actually go backwards.

You can get new tuning control switches, but they are hard to get hold off. One US expert suggested carefully drilling a small hole in the side of the switch (between the green segments) and squirting in switch cleaner.

I managed to get switch cleaner in the LCD display while doing this and had to strip it out and put in a new strip of white backing paper, courtesy of some glossy ink-jet paper. It now looks like new again!

It took a couple of applications of cleaner while rotating the switch to different quadrants, but it now works perfectly.

In all, the Lincoln is a great monoband rig for 10m, but is ideally suited to SSB and FM simplex. You used to be able to order a new “Superchip” from the USA that would give you repeater shift, but at £50 plus it costs half as much as an average rig. The Lincoln is a bit bulky, especially compared with the Albrecht 485S and you can’t easily work through 10FM repeaters either, but it works well on SSB.

I spent an interesting Saturday afternoon in early May with a 10m whip and my Yaesu 817 in the car as static mobile, but didn’t actually manage to work anyone with 5W and SSB/CW, which surprised me. Perhaps 5W and a compromise (loaded) antenna is not a good idea. Heard lots though so it was all good fun. I'll try the Lincoln/Albrecht next time.

Albrecht AE 485S for 10m

2009-05-07T03:54:00.000-07:00

Note: You can now buy the Albrecht (or the Magnum 257 as it is also called) at Amazon.

As the summer sporadic E season has started I thought I would drag out a couple of my 10m monoband rigs and see what I could work.

I thought readers might be interested in a quick review of the rigs, starting with the Albrecht 485S. This is also sold as the Magnum 257 which has a blue display background and not orange. Typical prices are around £199, although they come up on eBay secondhand for about £100.

The power output on mine is about 12W.

This rig is quite small and out of the box covers 28 – 29.7MHz. Press two buttons though and it opens up to include 25.160 to 29.699MHz in “bands”.

It is here that the rig shows its true background. It is really a CB, with AM, FM and LSB/USB modes.

As such it has some quirks that can be quite irritating to hams. Leaving it in ham mode and turning the tuning knob lets you move up and down the band in 10kHz steps. So far so good, but only if you want to work on 28.500, 28.510MHz etc.

If you want to work outside of these steps you have to press the “step button” which lets you switch to 1kHz steps. But now you have a problem. If you are on, say, 28.510MHz and hit the step button you can now tune from 28.510 – 28.519, but then it goes back to 28.510.

If you want to go 28.495 you have to switch back to 10KHz steps, move to 28.490 and start again.

This is really awkward and means that you can’t realistically use the radio mobile on SSB. However, its one saving grace is that it is brilliant for 10FM where 10kHz spacing is the norm.

The rig also has repeater shift, which is programmable. It took a few seconds to dial up 100kHz which is the standard and it will then happily tune 29.500 – 29.700MHz where the repeaters are –although I haven’t heard any European ones yet this season.

The rig also has an RIT, a noise blanker, a scan function and memories. On air it performed quite well, once you get used to the tuning.

I bought mine off eBay and some of the writing has worn off on the buttons, so watch that. I might try and get some new buttons.

The ability to scan the CB bands is also useful for finding out if 10m is about to open!

So, overall if you are looking for a lightweight, small mobile rig for 10FM it is brilliant. It is also OK for static mobile SSB work, but trying to move up and down the band while driving is recipe for disaster! Next the President Lincoln.

Update: I was able to buy some new buttons from Sharmans Wholesale for about £15 delivered.

International Marconi Day, 25th April 2009

2009-04-22T02:11:00.000-07:00

Saturday 25th April 2009 is International Marconi Day when stations around the world celebrate the birthday of Guglielmo Marconi.

it is also a good opportunity for you to gain a very nice certificate. All you have to do is work the requisite number of award stations and send in a log extract - you don't need QSL cards.

I gave a talk to my local club about the best way to win the award and you can download the presentation in PDF format (10Mb). It is aimed at UK operators.

You can also view my propagation predictions online.

You can find out more at: http://www.gb4imd.org.uk/

Pictured above are the operators at the Poldhu Amateur Radio Club who will be on this year as GB2GM.

DXing from a small (or no) garden

2009-03-08T04:47:00.000-07:00

This a is a presentation I gave to my local club. It talks about finding DX, the modes to use, what you can do with QRP and CW and also looks at a number of antenna designs and what I found.

I have made it into a 3.8Mb PDF and you might find it interesting, even without the narrative that obviously went with it.

Download the presentation.

Rybakov 806 vertical revisited - a stealth tree antenna?

2009-03-08T03:59:00.000-07:00

In an earlier post I talked about the Rybakov 806 vertical – basically, a 7.6m vertical end fed with a 4:1 un-un (unbalanced-unbalanced transformer), so giving a reasonable match across a number of bands.

In practice you MUST use an ATU to bring it down to 1:1.
Anyway, while playing with the design I tried wrapping the wire around an 8m fishing pole and had an idea.

If you push the pole up through the branches of a tree, taping each joint as you go, do you end up with a stealth antenna?
I think the photograph says sit all!

The pole is practically invisible and the leaves aren’t even out yet. Next to the matching box is a single earth stake and then two 20ft radials go left and right on the ground – you could bury them. I think it would work better with more radials.

My FT-2000’s built-in ATU was able to match it to 1:1 on 40-6m. The SWR on 80m is too high and the rig wouldn’t match it. Mind you signals were well down on 80m as the antenna is too short.

So how does it perform. On 40m it was either equal to or one S point down on an 80m 132ft OCF Windom on EU signals – you can just see the long leg of that in the photograph. Given the length is under a quarter wave this is quite good.

On 30m it equalled or outperformed the Windom slightly. This doesn’t surprise me as it is virtually a quarter wave on that band. The measured SWR was 3.6:1, which if you think about it is roughly 1:1 into 50 Ohms before it goes through the 4:1 un-un.

It was a similar story on 20m – equal to or just slightly down on the Windom.
The RR90 (Russian) beacon was down about 1 S point, the 4X6TU 9(Israel) and 4U1UN (New York) beacon was the same. VY2 (Prince Edwards Island) was down 2 S points. KQ2M (CT) was equal or slightly worse. K1RX (NH) slightly better.

It has to be said that compared with a dedicated half-wave horizontal dipole signals were generally 1-2 S points down, but that antenna is not multiband.

18MHz was barely open, but it was a similar story to 14MHz – roughly the same, some signals better, some worse.

21, 24 and 28MHz were not open, although as I have said before, it hears CB stations very well out to about 12-15 miles so I have high hopes for 10m.

So there you are - a stealth antenna that works from 40m – 6m for about £10 plus the pole. If you string the wire up into the branches you don’t even need the pole to be honest.

HF propagation prediction: February-April 2009

2009-02-18T08:04:00.000-08:00

The equinox periods provide longer daytime periods than winter, but logically, shorter night-time periods too. These tend to be the best months for working North-South paths, such as UK to South Africa.

On 160m (1.8MHz or Top Band), look for short-skip and DX openings at night. Again, no daylight skip is possible due to absorption, but openings out to 1,300 miles and occasionally further afield can be expected at night with conditions peaking around midnight and again at sunrise (greyline).

80m (3.5MHz) will generally follow the characteristics of Top Band at night, but will also provide good openings out to around 250 miles during the day. These will lengthen to around 500-2,300 miles at night with fairly good DX opportunities at times. At this point in the cycle 80m should still provide good DX as absorption is still quite low. Local communciation should be good as long as the critical frequency stays above 3.8MHz - register for the digisonde data at http://www.ukssdc.ac.uk/ionosondes/view_latest.html

40m (7MHz) Forty metres should open to DX in an easterly direction at sunset. Openings to the west should be possible after midnight and should peak just before sunrise. Contacts should be possible during the day, although, again, lower critical frequencies may mean that it is difficult to work other UK stations while perfectly possible to talk to European stations. If the flux rises then 40m may open up to NVIS contacts around the UK.

20m (14MHz) is likely to be the best DX band between sunrise and sunset. The bands may occasionally open after dark, perhaps to the southern hemisphere. Good openings will be possible during daylight hours out to around 2,300 miles.

17m/15m (18MHz/21MHz) should provide fairly good DX openings during daylight hours, especially to Africa and South America, with 17m being open more often than 15m. Once again, 15m may struggle to open during times of low solar flux, but could provide good openings if it rises above about 90-100. Both bands are likely to close after sunset.

12m/10m (24MHz/28MHz) These could be disappointing bands if the solar flux remains low. If the solar flux heads towards the high 80s/90s then openings will occur on both bands, although 24MHz will open first. If it breaks the 100 mark then expect to see some good DX openings on 10m, especially in early spring/late autumn.

The Rybakov 806 vertical

2009-02-06T05:27:00.000-08:00

I have no idea why this is called a Rybakov 806, but essentially it is a 7.6m vertical fed with a 4:1 Un-Un (unbalanced to unbalanced transformer) as described by IV3SBE.

It works very well with a fibreglass fishing pole and can be put up in a few minutes. The pattern (right) is what you get on 20m.

You need to put down an earth stake, and it really, really needs radials – the more the merrier.

The idea is that the antenna represents a non 1:1 SWR match at all frequencies – 7.6m is chosen as it isn’t actually a half wave (high impedance) or quarter wave (low impedance) on any band. The Un-Un (see below right) transforms the impedance to something closer to 1:1 and therefore reduces coax losses.

Does it work? I have tried a 7.6m Rybakov at a few locations and yes it does. Is it as good as a dedicated resonant antenna – no. You get losses in the Un-Un and there will always be a residual SWR on the feedline, which adds to the losses. You will also need to use an ATU to get the SWR down to 1:1, although most internal ATUs can usually cope with the mismatch.

As a matter of interest, here is the SWR I found with the 7.6m vertical (with the 4:1 Un-Un) with a single earth stake and two 20ft radials:

7.50MHz - SWR 3.2:1
10.1MHz – SWR 3.6:1
14.2MHz – SWR 5.6:1
18.1MHz – SWR 5.4:1
21.2MHz – SWR 2.6:1
24.9MHz – SWR 2:1
28.5MHz – SWR 2.1:1

The radiation pattern on 10MHz and 14MHz is typical of a vertical and good for DX. It is not so good on the higher bands as the antenna is longer than a quarter wave and gets complex.

It is also rotten on 80m (SWR 330:10) as it is waaaaay too short – if you extend the wire to 8.6m it will be better on 40m but you may as well make it a proper quarter wave (about 10.4m).

In tests it could hear local CB stations that were inaudible on my Windom, W3EDP or horizontal dipole. I know most CBers use vertical polarisation, but it shows that it might be good for low-angle DX radiation on 10m too.

It is a bit short for 40m, but does work. It was ok on 20m - some stations louder than on a Windom at 30ft, some worse. Same on 17m.

For 20m–10m use I think you are better sticking to 7.6m. The modelling shows that the radials are critical. You may get different SWR readings depending on how many you have. A single earth stake might give you a low SWR, but will be lossy.

If you have little space and like experimenting it might be worth a go, but I never found it matched a proper half-wave dipole at 30ft. More radials might help –if laying on/under the ground they don’t have to be resonant, just make sure they are roughly the same length as the radiating element and aim for as many as possible (32+ is good). If you try this antenna with just a ground stake I think you will be disappointed.

Let me know how you get on.

The W3EDP 85-ft end-fed

2009-02-01T07:53:00.000-08:00

This is one of my favourite, cheap antennas. I have been using one for years and they don’t get much simpler.

Mine was catapulted over the roof at this QTH. It goes out of the ground-floor shack window, straight up, over the roof and then down to the end of the garden where it is tied off with fishing line, leaving the end about 10 ft high. The counterpoise goes off at 90 degrees (see illustration).

At the last QTH it went 50ft up into an oak tree. It is very stealthy and a firm favourite of the QRP fraternity.

It consists of an 85ft wire fed against a 17ft counterpoise. Some books say that you don’t use the counterpoise at all on 10m. Others say that you use a 6.5ft counterpoise on 20m. You do need an ATU though.

Some even say that you should feed it as a balanced antenna through a balun, rather than as an end fed with the counterpoise connected to the earth terminal.

I have tried it both ways and it seems to work either way. The tuning is slightly twitchier using it as a balanced antenna.

The antenna works well on 80m and 40m and even gives a dipole a run for its money on 20m. I am writing this as I listen to US stations on 20m and Californian and Michigan stations are actually slightly louder on the W3EDP rather than the 20m dipole.

DX worked on this £5 wonder include 6W/DL4JS Senegal, YK9G Syria, VQ5XF Turks and Caicos, VP6DX Ducie Island and VQ9JC Diego Garcia.

The downside of the W3EDP is that it can be noisier than a dipole and watch for RF in the shack. Running it with an earth wire to a stake and a counterpoise my field strength meter shows that it isn’t too bad though. Try one.

G5RV on 80m - inverted V or flat

2009-02-01T07:17:00.000-08:00

After I posted my comments about how long antennas like the G5RV and Windoms don't like being set up as inverted Vs when being used on the higher bands such as 20m and higher, a friend asked if it makes a difference on 80m.

After all, for something like the UK's RSGB 80m club championship you need high angle NVIS communications.

I have found that it doesn't really matter what I use here - I get pretty much the same results. A G5RV, 85ft end fed (W3EDP) and full size OCF Windom all give signals of around S9 - S9+20db around the UK.

After modelling the G5RV in both inverted and flat modes with MMANA, it looks to me that it doesn't really matter. The performance on 80m is the same. See the plots (right)

The 20m EH Antenna

2009-01-31T09:07:00.000-08:00

The EH antenna attracts a lot of controversy - does it work and how? Is the coax doing all the radiating?

About two years ago I built a pair of EH antennas. I couldn’t really get either to work properly and they gathered dust in the back of the garage. In retrospect I should have used a choke balun near to the antenna. I moved house and couldn’t bring myself to throw them away, especially as I had bought a three-metre length of copper tube to build them that a cost of about £50.

Anyway, fast-forward two years and I thought I would have another go. I lent the small one to a friend to play with and set to on the bigger one.

I now have a 20m EH with two 20inch x 1.75 inch copper cylinders and a 10-turn tuning coil. It has a 10-turn choke 1 metre down from the antenna.

It is vertically mounted off a rafter in the loft and my other antennas are horizontal to cut down on cross talk/re-radiation effects. Does it work? Well, the 2.5:1 SWR bandwidth is just about 14-14.350MHz, the minimum SWR is about 1:1.4 and it hears almost as well as a dipole and a Windom, sometimes minus 1-2 S-points.

The noise level is lower too, which suggests little coax pick-up.

I have worked many stations, including Kazakstan and the recent Tunisian DXpedition with 59 reports - the latter on first try.

You can definitely see that fading is due to polarisation changes as one or other antenna improves as the other goes down. Does it work by Poynting Vector Synthesis? Don't know and may never know. Does it radiate from the coax? Don't think so (it has big choke near the feed point) and the fact that the field strength near the coax is less than my Windom and dipoles says something.

I have to admit that I am quite surprised. Earlier tests about two years ago were inconclusive, but I have learned that:

1. You need to earth the MFJ analyser to get reasonable readings.
2. You need the choke.
3. Make the tuning coil slightly longer than you think you need as you can always space out the turns to increase the frequency.
4. Spacing out the turns at the top of the tuning coil changes the resonant frequency, spacing out the bottom changes the SWR.
5. I did have it so that the maximum radiation according to the FS meter was the same as the minimum SWR, but this has changed slightly now that the antenna is on a different length of coax.

Does it work by Poynting Vector Synthesis? Probably not, but it does appear to work and the aim of this post was to encourage people toat least play with the design.

The noise level is lower too, which suggests little coax pick-up. I am only reporting what I am seeing. Build one according to the instructions and try for yourself. I was very sceptical and now I'm amazed.

For more details see http://www.eh-antenna.com/. You can get construction details at the EH Yahoo group (eh-antenna.yahoogroups.com)

G5RV – flat or inverted V?

2009-01-31T08:23:00.000-08:00

I did some tests recently with a G5RV in inverted V configuration. I was very disappointed. Don’t get me wrong, I know that the G5RV is a compromise antenna, but I found that some DX signals were inaudible compared with my 20m dipoles in the loft. Why?

Turns out that if you use a long multiband antenna as an inverted V it really changes the radiation pattern. The lobes contract quite badly and the radiation angle goes up dramatically. I lost about 7db east-west and the low-angle DX capability went through the floor.

An inverted V half-wave dipole doesn’t do this, so if you must have an inverted V for 20m, use a half-wave dipole, not a G5RV or OCF (Windom).

Save your inverted V G5RV or Windom for 80m where they seem to work quite well with high-angle radiation.

Above right: The red trace is a G5RV inverted V with the apex at 12m and the ends at three metres. The blue trace is a flat-top G5RV at 12m. These were produced with MMANA-GAL, an excellent program.

Greyline Propagation

2009-01-29T13:10:00.000-08:00

I few years back I was working on grey line propagation studies as part of my work with the RSGB's Propagation Studies Committee. For those who do not know what grey line is, here is a feature that was written for the RSGB's RadCom magazine. It is available in HTML form without images here or as an Adobe Acrobat PDF file with images (701kb) here.

Feel free to download them.

The first part of the research looked at trans-terminator propagation on 10m. That is, signal enhancements that are sometimes seen when signals arrive from areas to the west that are currently experiencing their local sunset. For this, Geoclock software was used (see www.geoclock.com), but the parameters are changed to show the illumination at both the D and F layers. This is done by following the instructions in the package. Signals were logged using DL4YHF's excellent Spectrum lab software (see www.qsl.net/dl4yhf).

The resultant data are processed using MS Excel and graphs can be produced like the one here. Enhancements were seen on signals from the OH9TEN and SV3AQR beacons, but it didn't happen every day. The phenomenon was called skip focusing.

Updates
You can also look at the latest trans-terminator results on 3210kHz (October 2005).
Radcom published the results of the first round of tests in May 2005 - you can download it in PDF format (500kb)

This is the original presentation on Greyline and the studies given to the RSGB Convention in 2005 (20Mb download - PDF.

Download the "3Y0X Propagation Predictions to G v Reality" presentation given at the RSGB's HF convention in October 2006 in either Adobe Acrobat PDF or Powerpoint formats (both 5mb). While not strictly about greyline it does show the effect of morning/sunrise enhancements on 80m very well. (October 2006)

Multi-band loft-mounted dipoles for 40, 20, 17, 15, and 10m

2009-01-29T13:03:00.000-08:00

Amateurs are always after the Holy Grail - an antenna that will work on all bands, is inconspicuous, effective, but above all inexpensive. Unfortunately, you seldom find something that fits all these factors.

This antenna has nothing new about its design, but it does bring together quite a few useful ideas and characteristics.

These are:

• Fully no-tune antenna system for five popular HF bands

• Suitable for SWLS, QRP, M3 licensees and PSK31 operating plus occasional useup to 100W, but watch out for RFI at high powers. DO NOT USE A LINEAR!

• Uses non-inductive (zig-zag) loading for 40m

• Feed point balun reduces RF pick-up and interference making it quiet.

Download the article in PDF format

Maldol MFB-300 HF vertical antenna

2009-01-29T12:58:00.000-08:00

The Japanese-made Maldol MFB-300 HF vertical is the latest antenna on the market to offer extremely wide-band performance, with a specified frequency range of 1.0-60 MHz.

There are very few antennas that can claim to work well across such a range and I was keen to see how it would perform. The benefits to a newly-licensed amateur, or one with very restricted space for antennas, are obvious.

The Maldol gives you access to all of the HF bands, plus 6m, and apparently all without the need for an ATU. I wasn't terribly impressed, but any antenna is better than no antenna I guess.

Read the full RadCom review.

The MFJ-1786 Magnetic Loop Antenna

2009-01-29T12:53:00.000-08:00

I have always been intrigued by small antennas. For those of us living in suburbia, seven element tribanders at 110 feet can only remain a dream. The quest therefore is always for electrically small antennas for HF that work.

Over the years I have experimented with magnetic loops, crossed field antennas and E-H verticals and have come to the conclusion that, for now at least, the magnetic loop seems to offer the best alternative to beams and dipoles if you have no space.

The MFJ-1786X is a 36-inch diameter aluminium loop that covers 10-30MHz. It can cover six HF amateur bands in one three-foot antenna, but the loop will also cover all the shortwave broadcast and utility bands in between as well. The loop is formed from 1.05-inch thick aluminium tube, which is welded to the loop’s variable capacitor so giving a very low loss connection – important for maximum efficiency.

If you thinking of mounting the loop in an attic do bear in mind that it can't be stripped down. Make sure that your loft opening can accommodate the 36 inches required or you will be taking a hacksaw to your ceiling!

Read the full feature as published in RadCom

Did Marconi really hear signals across the Atlantic in 1901?

2009-01-29T12:45:00.000-08:00

As far as the history books and the general public are concerned, Marconi is the father of radio.But Marconi’s main claim to fame all rests on a simple premise — did he actually receive signals from Poldhu, Cornwall, UK at Signal Hill, Newfoundland on December 12, 1901?

Unfortunately, some say the evidence is stacked against him and people have argued about the success or otherwise of his achievement for years.

Read Steve's feature from the December 2007 issue of QST on the work of the GB3SSS experiment (3Mb PDF).

Propagation predictions for International Marconi Day

2009-01-29T12:32:00.000-08:00

International Marconi Day (IMD) is a 24-hour amateur radio event held annually to celebrate the birth of Guglielmo Marconi on the 25th April 1874. The IMD event is not a contest: it is an opportunity for amateurs around the world to make point-to-point contact with historic Marconi sites using HF communications techniques similar to those used by Marconi, and to gain an attractive Award for achieving the requisite number of Marconi stations worked (see IMD Award ).

IMD is usually held on the Saturday closest to Marconi's birthday, when amateur radio stations are established and operated from original historic sites, or nearby. These stations are known as the 'Award Stations'. This year's event is on Saturday 25th April 2009.

I have calculated some propagation predictions from the UK to the various stations taking part to help you make contact and win your award.

Right: The Marconi Centre at Poldhu, Cornwall (or the "Macaroni Centre"as my kids call it!).