Tuesday, 19 June 2018

Fixing the 20m QCX radio


I've had my 20m QCX kit working now since just after Christmas. While the build was quite straightforward I did have a few problems.

Click to enlarge the photograph by the way.

The first was that I managed to blow the 7805 regulator while leaving the radio running on WSPR one morning. Having replaced that I found that the rig was quieter and there was no TX output any more. Thinking I had also blown the PA transistors I replaced all three of the BS170s, but that didn't help either.

Anyway, after a lot of help on the QCX reflector I decided that the fault had also taken out the 74ACT00N chip. This had been soldered onto the board directly so had to be cut out with a Dremel and a new IC socket installed.

And after finding a short somewhere near the PA transistors all was well - success! Output using a 12.6V Lithium battery pack was about 1.8W

I have been using it on and off ever since as it has a really nice receiver - even took it to North Norfolk as I detailed in another post.

But one thing always bugged me - why only 1.8W? When I built it originally I was getting more like 3W, so perhaps it was the replacement BS170 transistors, which came off Ebay on a slow boat from China.

So having a few hours free today I ignored my own "if it ain't broke don't fix it" mantra and pulled it apart. I replaced all three BS170s with new ones bought from the GQRP club and while I was at it I replaced C22 with a 0.1uF capacitor to try and soften the sidetone a little.

I managed to break one of the wires to one of the control buttons on the front in the process, but it is now all back together.

And the power output is now just under 3W with 12.6V - success! I have no doubt I could get more if I messed around with the band pass filter, but I don't think it is worth it. I tend not to run it on 13.8V as the regulator gets VERY hot indeed.

Anyway, it is a great little radio and will be going on some more journeys no doubt.

I can thoroughly recommend it as a kit project - see QRPLabs site. My case came from Banggood in China and only cost  a few pounds. It did take about 10 hours to machine (posh word for drilling out with a Black and Decker and attacking it with a file).

The label was produced in Photoshop and printed off by Photobox.co.uk. I ruined the first one by spraying it with varnish, which made the dye run. Luckily I have a few more spares and may eventually cover one in sticky-back plastic. But for now it looks great.

The red buttons were bought just before Maplin went bust so are a lasting tribute to what was one of my favourite shops and the result of much ribbing by the family every time I went there - RIP Maplin.

Thursday, 24 May 2018

"Bumps on the Air" 2018 - QRP in North Norfolk, UK


Today was 2018 ”Bumps on the Air” day for me. Because we don’t have any summits in Norfolk I have to make do with tiny hills, or bumps!

Two years ago Jim G3YLA and I climbed up Beeston Bump (63m) and did some amateur radio operating. This year I wanted to beat that so drove to Norfolk’s mightiest peak – Beacon Hill near West Runton at 103m. Ta dah!

Actually, this wasn’t a very exciting spot as there are just two rotting benches, a flag pole and trees all around.

Nevertheless, I set up my end fed half weave vertical on a 10m fishing pole and connected up my Yaesu FT817. There wasn’t too much about but I worked John F5VKU (also G8MM) near Cannes with 5W SSB. He said he was struggling to hear me.

My 20m QCX radio - click to enlarge any image.
After playing with SSB for a bit and failing to break some pile ups I connected up my 20m QCX radio and tried some CW. I was really surprised as Karl IV3RJH came back to me, 559/549 both ways. I was running about 2W, he was running 3W.

I do have to fix the sidetone on the QCX as calling CQ sounds more like “thump-de-thump-thump-thump-thump-de-thump”. I have the new capacitors, but am waiting for some new BS170 transistors so I can hopefully up the power level to more like 4W too.

But the QCX is an amazing radio for the money and hey, I built it myself, complete with the case and custom label, so any QSO makes me smile.

Another 20m SSB session with the FT817 and I bagged Jack OH3GZ and Juha OH6QAZ.

At this point I packed away and after lunch headed for Beeston Bump on the coast near Sheringham. I’ve written about this before as it has a fantastic view over the North Sea.

Anyway, I put up the EFHW vertical for 20m and set to with 5W CW from my Elecraft K1. This raised Gert OH/DL7UG and Dima RW4C. I then bagged Fabi IK5IiS near Florence.

Also heard were stations in Cypus and Canada, but the Cyprus station on SSB couldn’t hear me and the Canadian seemed to be sending his life story in CW to another station and I got fed up waiting to call him!

I also had a play with my 3W MTR3, but didn’t work anyone as I could see rain clouds coming and decided to pack up.

So not a bad day’s radio. The Elecraft K1 and Yaesu FT-817 worked flawlessly. I think I was getting some RF into the keyer on the QCX as I had trouble sending “/P” – the “/” turned into a right mess sometimes, although I had no trouble sending it on the K1 with the same Palm Paddle.

The moral is that life is NOT too short for QRP!

Update: I checked the reverse beacon network last might and saw that I had been picked up across Europe while calling CQ, but often with no response. Some of these SNR figures are quite large too. In other words I was loud enough.

That's a shame as it would have been nice to have worked some more stations.

Is this because of a lack of activity? Or is it because, as I often wonder, that a lot of people have moved to FT8?

Tuesday, 1 May 2018

IBP propagation predictions for the UK for May 2018

Propagation predictions for the International Beacon Chain
for the UK, May 2018.
In an effort to try to make HF propagation predictions more accurate I have been playing with a different method of producing them using the ITURHFPROP software.

Previously I had been calculating the field strength of each beacon and then converting that to an S point level. It was pointed out that this isn't the best way and that calculating the signal strength in dBm and then converting it would be better.

They are based on 100W to a dipole at 10m - we know that the IBP chain use a Cushcraft R5 antenna.

I then hit the problem as to what antenna gain do you use. This may sound simplistic, but in fact it isn't as the actual gain off a dipole will depend upon its height, its orientation and the required take-off angle.

Now, the take-off angle will depend upon what ionospheric mode is dominant at that point in time. That is, is it one F-layer hop, two F-layer hops or a combination of E and F-layer hops.

After a lot of thought and discussion I settled on setting the gain at both ends at 0dBi, which appears to give reasonable results - setting it at 2.15dBi gave over-optimistic results

Anyway, attached is the plot of predictions for the beacon chain for May 2018. I'll check to see how accurate it is and adjust the input files accordingly. The ultimate goal is to the transfer these settings to other HF predictions.

If anyone wants to report on whether they find these accurate or not please let me know. They are median predictions, which means some days may be better, some days worse.

Just click on the chart to enlarge it.

Sunday, 22 April 2018

International Marconi Day 2018 from Caister Lifeboat

Chris G0DWV on the mic. with Roger G3LDI looking on.
Norfolk Amateur Radio Club managed to contact 116 other radio amateurs in 23 different countries on Saturday 22nd April 2018 when we took part in the annual International Marconi Day (IMD) event to mark the inventor's birthday.

This was the ninth year we've taken part.

Using the call GB0CMS and a mixture of Morse code, telephony (speech) and data (FT8), contacts were made with other radio amateurs across the UK, Europe, and the USA.

Notable contacts were made with other IMD stations in Italy, Ireland, Weston-Super-Mare and Poldhu, Cornwall – home of the Marconi Centre from where the inventor made the first transatlantic transmission in 1901.

We ran the all-day special event station at Caister Lifeboat to commemorate the village's original Marconi Wireless Station, which was established at Caister in 1900. The station was in a house in the High Street known as Pretoria Villa and its original purpose was to communicate with ships in the North Sea and the Cross Sands lightship.

Conditions weren’t brilliant due to a major solar disturbance (effects of a coronal hole), but we were still able to cross the Atlantic on three occasions.

We were picked up in Pennsylvania, US via FT8 at -20dB on the reverse beacon network, but didn't make any transatlantic FT8 QSOs.

The equipment used was 100W maximum from an Icom IC-7400 (20m) and an Icom IC-7300 (80/40/30m). Antennas were a W5GI dipole on 40m and my design of a monoband end-fed half-wave (EFHW) vertical for 20m. The FT8 digital mode was used for the first time to show what can be worked with just 20-25W.

We also used a Flex Maestro to remotely link into Malcolm G3PDH's home station via the internet and worked back to ourselves using his special First Class Operators' Club call for April, G4FOC. The Maestro is very impressive!

Above all, it was great fun and a good social event

Sunday, 11 March 2018

Commonwealth Contest 2018 and QRP


RSGB certificate for 5th place QRP section.
Update: It turns out I came 5th in the QRP section of the 2018 Commonwealth Contest. I lost two QSOs for being "not in log",  and lost 4th place by 10pts to Dave G3YMC (which is how it should be!). Great fun and I'll do it next year, probably with my Yaesu FT817 and the addition of an EFHW vertical for 20m too.

I took part in the 2018 Commonwealth Contest this weekend on HF CW. This was always going to be a casual entry as I had other things to get on with over the weekend, not least was helping tidy the house for Mothers’ Day on Sunday!

I decided to enter the QRP category with a maximum of 5W. One reason was I knew that my good friend Dave G3YMC had won the category last year with 30 QSOs. I mean, how hard can it be to beat 30 Qs with 5W? Answer: very hard apparently!

I got going with 20m and quickly worked four stations in Malta and Cyprus. I also cracked off some of the UK HQ stations on 80m for 25pts apiece.

The afternoon saw openings to Canada, which brought in a few VEs. I was also happy to work the Cayman Islands and G3TXF on Mauritius.
My multiband fan dipoles in the loft.
Only used with QRP for EMC reasons.

Ionospheric propagation conditions were lousy with no sunspots and a geomagnetic disturbance the night before.  Fifteen metres was closed so it was a 80, 40 and 20m only event.

What you quickly realise is that many stations are using the full legal limit, so might be running 400-1,000W. If they aren’t very strong they probably won’t hear your 5W QRP station - fact of life!

So there were lots of “NR?” being sent for repeats, if they came back at all.

I went to bed about 23:30hrs and set to again at 06:45hrs. At that time 20m was dead, but there were some 40m and 80m contacts to be had and I managed to get VE in the log again. I also swept up the remaining G, GD, GI, GJ, GM and GW HQ stations as these were quite easy with 5W.

The antennas were my loft-mounted fan dipoles for 40-10m, which beat the outdoor multiband 80-10m end-fed half wave and W5GI dipole on 20m - go figure. I used the EFHW or W5GI for 40m and 80m, depending on which gave the best signal.

The “nearly” category included QSOs with Singapore, Australia, Gibraltar, New Zealand and Zambia - I just wasn’t loud enough. But hey, Cayman Islands, Canada, and Mauritius on 5W will do me!

Next year if I do it again with 5W I might put up a monoband 20m EFHW and perhaps use my Yaesu FT-817 (I don’t currently have a CAT cable for it), although the IC-756 Pro3 band scope is handy and it is an excellent rig, even when backed off to 5W. Logging/keying was with N1MM+, which worked flawlessly.

All good fun and 30 Qs won’t win it ( the highest QRP entry so far is C6AKT with 92 QSOs), but my unconfirmed overall score was higher than the 2017 winner’s, so not too shabby.

The Commonwealth Contest is a great one-weekend opportunity for UK stations to work DX with no big pileups.

Tuesday, 23 January 2018

IBP beacon predictions for UK using ITURHFPROP

Over Christmas and the New Year I got better acquainted with the ITURHFPROP propagation prediction software.

This is the software that Gwyn G4FKH uses to produce the monthly HF predictions for RSGB’s RadCom magazine and which was produced by the ITU.

Gwyn adapted it to produce a graphical output, which can be found at www.predtest.uk

But I was intrigued to see if I could use it to produce some predictions for the worldwide International Beacon Project (IBP) chain that runs on 14, 18, 21, 24 and 28MHz. I won’t go into too many details here about the IBP network as you can find all you would want to know at http://www.ncdxf.org/beacon/

The good news is that as they all use the same power output (100W max.) and the same antenna (pretty much a unity gain or +2.15dBi antenna) it should be fairly easy to model what the expected signal strength should be here in the UK.

ITURHFPROP runs in Windows and uses an input file with all the parameters needed, such as your QTH lat. and long., the transmitter’s lat. and long., required SNR, bandwidth, smoothed sunspot number, power etc etc.

You then run it from the command line and it creates an output file.

I ended up creating input files for each of the beacons, and a spreadsheet that can take each of the output Field Strength (dB(1uV/m)) figures and convert them into S units.

I then created a batch file that runs all of the predictions for each of the beacons in one go. With an I5 processor this takes less than about 15 seconds.

The spreadsheet then formats these so that I can produce the chart you see on the page. This may sound long-winded, but it really doesn’t take long. I’m sure someone with Python programming skills could automate the whole thing, but I wanted to make sure it worked first before going any further.

The end result has proved to be quite accurate and shows that at this point in the sunspot cycle we can’t expect miracles in terms of hearing the distant beacons. While some are audible on 14 and 18MHz, generally we are not hearing much above that.

In the UK, what have been audible quite regularly this month on 14.100MHz are RR90 (Novosibirsk, Siberia), CS3B (Madeira), 4U1UN (New York) and occasionally 4X6TU (Tel Aviv).

It also shows what the effect of an elevated K index can be as this generally means the beacons are less audible (if there at all) as the MUF declines. We have been suffering from the adverse effects of coronal holes recently and that isn't going to end any time soon.

You can see the predicted MUF over different path lengths in near real-time using the graphed ionosonde data for the UK at http://www.convectiveweather.co.uk/ionosphere/graphs.php?type=live

This was produced by fellow RSGB Propagation Studies Committee member Jim G3YLA and his colleagues at Weatherquest in Norwich.

I’ve posted the predictions here to see if they are of interest to anyone. If they are I’ll update them monthly.

To view the January IBP prediction chart full size just click here.

Friday, 22 December 2017

Radio Caroline back on Medium Wave

The Orford Ness masts
If you fancy a bit of nostalgia you can now listen to Radio Caroline again on 648kHz AM on the medium wave.

The famous pirate radio station needs little introduction, but is now broadcasting legally using (ironically) the famous Orford Ness antenna system on the Suffolk cost, formerly used to transmit the BBC World Service in English around the clock on 648 kHz from September 1982 until March 2011.

The station was founded in 1964 to play pop music all day at a time where broadcasting was dominated by the BBC and pop was played for an hour a week.

Caroline was one of five stations granted a community radio licence by Ofcom and is now running 1kW, but with a really good antenna mounted right next to the sea.

The station is 59+20dB at my home QTH 10 miles south of Norwich (JO02NN) using a Perseus SDR and a homemade 1m active loop mounted in the loft. It is also easily heard with a portable radio.

Radio enthusiasts around Europe might like to listen for it.

More information:

Orford Ness transmitter:
https://en.wikipedia.org/wiki/Orfordness_transmitting_station

Radio Caroline:
http://www.radiocaroline.co.uk/



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