HF Propagation at Sunspot Minimum

The effects of coronal holes are likely to continue for a
couple of years.

This weekend I’ll be giving a talk at the RSGB conference on “HF Propagation at Sunspot Minimum.”

This will show that we can expect the minimum to be around late 2019 or 2020. It is hard to be precise, as the minimum is something you can define after the event, not before or during!

What I will say is that we can probably expect the effects of solar coronal holes to continue, at least until we are well into the minimum.

Geomagnetic storms can cause problems on HF, although they can also bring short-lived ionospheric enhancements so they are a double-edged sword.

For example, on Tuesday 10th October the bands were open to DX all the way up to 12 metres. But as the solar wind from the coronal hole hit on Wednesday, apart from a short-lived ionospheric enhancement the MUFs took a dive.

By Thursday (12th) lunchtime, 20m was struggling to fully open and 17m was showing very little activity indeed. But by Thursday afternoon, and with a K of 5,  I had worked Saudi Arabia on 10m SSB.

This shows that at sunspot minimum with a solar flux index of just 66, quiet geomagnetic conditions may be better than stormy ones. So look for a K index in three 0-2 range, not 5-7! But then again, when solar plasma first hits the earth we may get some short-lived enhancements right up to 10m, so a high initial K index can work for us.

For those who weren't at the lecture, I showed that monthly average maximum useable frequencies will decline with the sunspot number. This doesn't mean there won't be F2-layer openings on 21MHz and higher, just that they won't be as reliable or as long lasting.

Other than that I encourage people to play with a propagation program to get an idea of what might be possible.

My suggestions are:

Windows based

VOAProp

HAMcap

W6ELProp (when installing, right click and run as administrator on Windows 10)

VOACAP


Online

VOACAP.com

Predtest.uk


Other sources of info I mention are:

Solarham.com

NOAA – Space Weather Prediction Centre

Real-time F2 critical frequency display (this will soon move to Propquest.co.uk)

Smoothed Sunspot Numbers

Latest extreme UV image of the sun from the Solar Dynamics Observatory spacecraft (shows coronal holes)

Lastly, I talk about the difficulties of predicting openings with FT8. One suggestion is to use VOACAP and set the required SNR to a figure of -20dB or so. It is usually set to about 24-31dB for CW and 45 for SSB. This is still experimental (as some SNR figures are quoted as dB per Hz, while others are quoted in a 2500Hz bandwidth), so you might have to play with it. VOACAP’s settings are critical and it is worth reading the notes on the VOACAP website and also the “Top 10 mistakes in using VOACAP”.

Visit to NI6BB, USS Iowa, San Pedro, California

The big guns of the USS Iowa.

As many regular readers of this blog may know, I try to visit as many special amateur radio stations as I can when working overseas.

This week I am in Long Beach, California again for a conference and it was an ideal opportunity to visit the famous battleship USS Iowa in nearby San Pedro, which has an amateur radio station with the callsign NI6BB.

USS Iowa (BB-61) is a floating maritime museum that is well worth the visit. It has a rich history that spreads from World War Two, through the Korean conflict in the 50s, and the cold war before it finally became a museum in 2012.

US Navy veteran Jerry Johnson with
one of the 110lb powder sacks.

Its main battery consisted of nine 16 in (406 mm) Mark 7 guns, which could fire 2,700 lb (1,200 kg) armour-piercing shells 23 miles (37 km). On the tour you find out how they used to load the guns with six 110lb silk sacks filled with powder, which when ignited with a single cartridge would rapidly burn in one third of a second, firing the 1,900 lb (862 kg) shell out at 2,690 feet per second (820 m/s).

The USS Iowa discone-cage HF antenna,
complete with plastic owl!

The other statistics are staggering (including 19.7-inch armour plating), but I’ll leave you to Google them.

Anyway, back to the radio, the radio room on the Iowa is well equipped with a Kenwood radio for HF.

On the bow of Iowa is the discone-cage antenna. Fed at the top it is a discone providing coverage from approximately 10 to 30 MHz with a VSWR below 3:1. The antenna has a plastic owl on it to stop pigeons resting - but they ignore it apparently!

Ron Frank N3HI let me operate some 20m SSB from the ship, as I have G0KYA/AB8ZV UK full and US Extra Class licences, and I worked a few stations including Washington State and Ohio. One was a “nearly” as I couldn’t quite get his full call before he faded away, which was a shame. HF conditions weren’t brilliant.

There were one or two loud stations on CW, which they often work, and Ron says they tend to operate a lot of digital too, including FT8.

Anyway, my thanks to Ron for letting me play for an hour and giving me some detailed history of the USS Iowa. If you are ever in the Long Beach/San Pedro area go and visit. It is truly fantastic.

My thanks to Ron Frank, N3HI.

I also revisited W6RO, "The Queen Mary", in Long Beach, California where I am staying. I operated from there in 2012 and they always welcome visiting radio amateurs. We had a long chat about UK and US amateur radio.

If you are interested in some of my other historic radio visits you can read about:

• NI6IW - USS Midway, San Diego, California
• W7SUB - the USS Blueback, Portland, Oregon
• K6KPH - The Maritime Radio Historical Society, Point Reyes/Bolinas, California

Elecraft K1 discontinued

Elecraft has announced that it has discontinued the K1 transceiver. I'm not surprised as this had been predicted some time back.

Component availability had been an issue, and technology has moved on.

Luckily, a local ham managed to get one of the last K1s after reading about them - and seeing this blog.

I'd like to thank Elecraft for producing a great little radio and for supporting QRP. There's always the KX2 and KX3!

CW fun with the Elecraft K1

I haven’t had much of a chance to get on the radio recently – the day job has been getting in the way!

So I thought I would put my Elecraft K1 into action yesterday evening and see what could be done with 5W of CW. I built this rig last year after having the kit in the loft for about 12 years – you can read about that here.

The great thing is it only has two bands 20m and 40m. This focuses the mind and stops you QSYing to other bands left right and centre.

So, I hooked up to a W5GI dipole and a 65ft EFHW (with loading coil for 80m too) and switched on.

The first station worked was OZ7BQ, Joe near Copenhagen, on 7.026MHz. I had to double check his name as it shows on QRZ.com as Hans Jørgen, although he definitely sent “Joe”.

Then it was IQ7AF on 7.028MHz, a special event station in Southern Italy.

Joe OZ7BQ

Staying on 40m, I narrowly missed Mike GM0HCQ/MM on the James Clark Ross, a research ship just off the coast of Norway and heading for the Arctic.

Then it was on to II2FIST on 20m, celebrating 30 years of the FISTS CW group. Managed that on first call despite a pile-up – not bad with 5W.

And to round the evening off I made contact with Doug ZP6CW in Paraguay on 20m. Other countries heard but not working included Norway, Serbia, Germany, Russia and Czech Republic.

This isn’t to brag, just to show what you can do with 5W CW from a kit-built rig and a compromise antenna. All the 40m contacts were on the home-made W5GI dipole. Half of the 20m ones were with the multi-band EFHW.

I think 5W SSB would have been a different story.

Solar and HF Propagation Update

I haven’t written about the state of the sun and propagation recently (apart from my weekly HF contribution to the RSGB’s GB2RS report).

So, it seemed like a good idea to publish an update.

It is now July 2017 and the sun is completely spotless. The solar flux index (SFI) is 72 and the sunspot number is zero (as you might expect).

Given that the SFI never goes below around 65-66 this shows just how spotless the sun actually is. And current predictions are that we will hit sunspot minimum in 2019-2020.

As the Solar Influences Data Center (SIDC) says “As the current solar cycle 24 gradually gives way to the new solar cycle 25, several consecutive days and even weeks without sunspots will become the norm.

“The previous minimum surprised scientists and solar observers by being the deepest in nearly 90 years. Will the upcoming solar cycle minimum show as many spotless days, or will solar cycle 25 take off much faster than expected?”

For this we will have to wait and see.

The first sunspot of solar cycle 25 has already been spotted (December 2016). Its high latitude (23°) and reverse polarity showed that it definitely belonged to the next sunspot cycle.

But don’t get too excited as sunspot cycles usually overlap, by up to four years. This again, might put the solar minimum into 2019/2020.

The sun with coronal holes on 5th July 2017.

Meanwhile, we are still suffering the effects of a series of coronal holes (CHs). These are areas of the sun with “open” magnetic fields that allow the solar wind to pour out. If Earth-facing these can result in an increased K index, an initial propagation enhancement, and then probably reduced MUFs, noisy bands and possible aurora.

CHs are a feature of a declining solar cycle, but should eventually subside a little. The best way to predict their effects is to look at the sun in extreme ultraviolet light using the SDO spacecraft and look for dark patches. If a CH is on or near the sun’s equator and earth-facing we might expect the impact of the solar wind in perhaps two days, although this can vary depending upon its speed.

So at the moment the low SFI means that, other than sporadic E openings, we can’t expect the maximum useable frequency over 3,000km to climb much above 14 or perhaps 18MHz.

So if you want F2 layer DX concentrate on 30, 20 and 17 metres.

In the Northern hemisphere we are in the summer doldrums with lower MUFs during the day, but higher MUFs (than winter) in the evening and night.

This is due to a change in the ionospheric chemistry with a shift towards more diatomic species and fewer monatomic ones. These are harder to ionise as they are more tightly bonded, hence the lower levels of ionisation.

One quick tip. Don’t write off 20m and 30m in the late evening – they might still surprise you with some DX.

Playing with the propagation prediction system at Predtest, which uses the ITURHFPROP engine and is managed by Gwyn G4FKH, will give you some idea of what band may be open to where.

What we can say is that good DX paths, such as transatlantic and far eastern, will return in the Autumn, perhaps late September – but the lower HF bands, 30, 20 and sometimes 17m will still be the “money bands” for DX.

A Predtest prediction for 20m at 21:00UTC in July 2017 for the UK. the smoothed sunspot number being used is 18.

Soda Pop 40m CW QRP radio now finished

The finished 40m Soda Pop QRP radio (click to enlarge)

I finally finished the 40m 5W Soda Pop CW radio by Steve Weber KD1JV.

Building the board took about 8.5hours. But preparing the hardware from scratch took a lot longer.

I used a Hammond die cast box and drilled the hole for the controls. I then chain drilled, cut and filed the aperture for the display. My metalwork skills are limited to what I can do in the garage with a Bosch drill and a selection of files.

I ended up having to elongate the holes for the controls and turn the hole for the antenna connection into a slot, otherwise I couldn't get the board in at the angle required. As a result I had to make up a plastic blanking plate for the back.

The box was painted with Plasticote metallic blue and gloss varnish.

The finished 40m Soda Pop QRP radio (click to enlarge)

The panel label was produced using Photoshop and a photograph of mine of Happisburgh Lighthouse in Norfolk (we don't have any summits as it is very flat!).

Once I was happy I then used Photobox to produce five copies of the photograph (in case I screwed a few up) and lacquered that too.

The whole thing was assembled after the front panel was stuck on with red Spraymount.

I'm happy with the result, although I might do the front panel again at some stage to get the hole alignment a little better and also lacquer it with a matt rather than gloss varnish.

Things I learned:
1. Metal cases take a lot of work to get them right!
2. Measure, measure and measure before cutting and filing.
3. When chain drilling, make the aperture too small at first and open it up with a file.
4. Choose a dust free spot to do the painting - a dusty garage floor is not ideal
5. Let the paint harden for about a week to avoid fingerprints.

Now, the fun can start and I can use it a bit more.

So far I have worked Italy, Ukraine, Poland, Germany, and Estonia with it. Many thanks to Steve Weber KD1JV for a great little design.

I'm planning a Norfolk "Bumps on the Air" (BOTA) outing with it quite soon.

Steve G0KYA

Soda Pop 40m QRP Transceiver S/N 011 lives!

The board for the 40m Soda Pop QRP radio (click to enlarge).

I was lucky enough to get my hands on a Steve Weber KD1JV-designed Soda Pop single band QRP CW transceiver kit recently. Soda Pop is meant to be a play on "SOTA Op" as it is meant to be a lightweight portable radio for "Summit on the Air" operators

Steve only produces a design every two years or so and they instantly become classics. It is a lottery as to whether you are lucky enough to get one and this time I was. My other KD1JV rig is a 3-band 3W Mountain Topper Radio, which I built myself (you can now buy them ready made via LNR precision).

All of Steve’s rigs are fantastic, tricky to build as they are nearly all SMD, but offer fantastic performance. You can blame Colin M1BUU for getting me into these. Colin’s Steve Weber rigs are works of art and regularly go up mountains for SOTA.

As I live in Norfolk (which is very flat) I have to make do with the odd hill!

I’m happy to report that my 5W 40m Soda Pop rig is now built and working well. 

Built using hand soldering over a period of a few days – a total of about 8.5hrs – I was delighted to find it worked first time. Sensitivity seems good and power output is 5.1W with a 12.3 V Li-Ion battery.

I aligned it by ear as I don’t have an oscilloscope and got it close. It was perhaps 20-40Hz off frequency, but a quick tweak in the calibration mode got it pretty much spot on.

Note the tiny SMD components - all hand soldered
(click to enlarge).

The BFO was setup by ear too.

So did the build go without hiccups? Hell no! The following points might be useful to other builders.

1. As always with SMD take great care with the components. Transistor Q14 “pinged” off at one point never to be seen again, or so I thought. As luck goes, I found it three days later under a desk lamp - 10 minutes after I had ordered a replacement off Ebay!

2. Follow the instructions religiously and only take out the components one at a a time. This saves them getting muddled up as many have no markings.

3. Take extra care with the band-specific components as it is easy to get it wrong. I ended up mistaking some inductors for the capacitors and had to remove them. If in doubt check them with a multimeter to make sure they are inductors and not capacitors. This may be why some people are reporting deaf receivers.

4. When you do the initial alignment and are peaking CT1 and CT2 make sure you have actually turned the volume up. Doh! Even with the volume turned down you will hear a hiss, which you may mistake for band noise. Don’t ask me how I know!

5. Note that not all the component locations are actually used, including C10, C49, C59, C6 (on some bands) and D2.

6. As you identify components  bag the spares up in marked bags as you will need some of them when you build the top of the board.

7, When soldering the power socket make sure it is square to the board - mine had twisted slightly and had to be de-soldered and done again.

8. Make sure you have the right number of turns on the two T39 toroids. Putting the wire through the hole counts as one turn. 

Anyway, it is early days for the Soda Pop - the 40m band was in lousy condition today and there were only a few signals on, but they seemed about as loud on the Soda Pop as my IC-756 Pro3. I’ll try it again tonight when the band should be better.

The RBN shows I was being heard in Germany and
Scotland on 7.030Mhz

A CQ call on 40m resulted in me being heard by DF7GB, DJ2BC, DJ9IE and GW8IZR via the Reverse Beacon Network at up to 20dB SNR at 13:50UTC. 

The hardest bit now will be boxing it up - I have a Hammond 1550M Die Cast Box, but that will need some serious metalwork (cutting, drilling and painting) so it will no doubt take longer than the build-up of the board.

I’ll add a photograph as and when it gets done.

My thanks (again) to Steve "melt solder" Weber, KD1JV.

Steve G0KYA