Tuesday, 2 August 2016

More great tins for QRP radio projects

Click to enlarge
Regular readers will know I've built a couple of QRP HF radios into mint tins. The first was a 20m Rockmite ][ built into a Stewarts' tin with a Spitfire on the front. 

The second was a 40m Foxx-3 built into a Stewarts' train tin.

This all came out of a desire to build something in an Altoids tin or similar having been inspired by the fantastic radios built by Colin M1BUU.

He showed me a Steve Weber-designed ATS (Appalachian Trail Special) in an Altoids tin at a Rishworth QRP convention and the workmanship was fantastic.

Anyway, both my radios work, but at around 1W or less QSOs can be quite hard work – must dig them out again soon and have another play.

But this has set me on the trail for more and better mint tins and I found a couple of crackers recently.

The first depicts the White Star Line and was bought for £3.50 at the Bressingham Steam Museum in Norfolk. They had other designs and it appears to be made by a company called Half Moon Bay in Bath. They are a wholesaler, but do have links to an online stockist – Kitsch-a-go-go – which has lots of different tins.

The second tin was found at the British Motor Heritage Museum at Gaydon and depicts an MGA sports car. It is also a little bigger than an Altoids tin and cost £4.

This was made by a company called Red Hot Lemon. It has a minimum order of £100 unfortunately, but you could always club together with someone else to buy some.

Now, all I need is another kit to build. What I'd really like is a 3W 40m and/or 20m radio transceiver, preferably synthesised so that you move around in frequency that would fit in a standard Altoids tin. So basically, a Steve Weber ATS or MTR – shame they are not being made in kit form. I have a three-band MTR v2 which is my pride and joy.

If you know of any other suitable kits please let me know by commenting below.

Thursday, 28 July 2016

Repairing a cross-needle SWR meter

The SWR meter - working 100% again.
I've owned an AEA ET-1 antenna tuning unit for the last 20+ years. In that time I've had to replace the inductor switch as it burned out and also replace the meter.

Luckily, it uses exactly the same meter as MFJ ATUs so I was able to buy a replacement from them. I also resprayed the case at some point.

But recently the meter started playing up – it would only indicate 20W maximum forward power instead of 100W.

It was more of a problem on the less than 30W setting as I often use QRP radios and need to know if I am putting out 2W or 5W.

You could ask “why not just bin it?”, but that's not in my DNA!

Anyway, after asking for advice on the CDXC forum and looking at the schematic I decided that it could only really be down to a failed capacitor, resistor or diode. Given that semiconductors would be the first suspect I ordered two new 1N270 diodes from a UK supplier on Ebay for £3.98.

When they arrived I unsoldered the old ones, and checked them – one measured 1K Ohm resistance in both directions – not good and definitely not diode-like behaviour.

I soldered in the new diodes and bingo the meter is back to normal again. I've since ordered some 10 more 1N270s from China for just £1.12 inc. postage. These will do as spares.

I'm writing this as it might be useful to owners of cross-needle SWR meters in future. If you start to get low readings it may be the diodes. If you get no reading at all it is probably the meter.

Friday, 22 July 2016

Elecraft K1 QRP radio finally finished

My Elecraft K1 (click to enlarge)

You could say that this project has been a long time in the making. The kit for this Elecraft two-band (40m/20m) K1 5W CW radio was actually a Christmas present back in 2004.

Heck, I still have the invoice for $329 plus the £44.97 import duty, making it about £230.97 at the exchange rate of the day (nearly £300 at today's rates).

When I first got the kit I had a couple of reads of the instruction manual, went “wooah” and put it in the loft. It even moved house with me eight years ago.

Anyway, a conversation with Colin M1BUU (a more enthusiastic QRP builder and SOTA operator you couldn't wish to meet) at the 2014 G-QRP Convention convinced me that I really should put it together.

In the intervening 10 years I have built a lot of other kits, including a Hunter SDR, Rockmites, MKARS 80 and a Steve Weber MTR, so I had picked up a lot of construction skills.

Last Christmas I actually started the build and, while not difficult, it was time consuming. Fast forward to July and I thought it was about time I finished it.

The build wasn't too bad, but I had a few problems, such as the wiring on the multi-turn pot for the VFO control – I thought the numbers on the side of the pot represented the numbers in the manual. They didn't.

I also managed to loose a couple of components down the back of the bench, which were subsequently found, and also couldn't find the insulating spacer for the power transistor – this I managed to improvise with insulating tape and fibre washers.

The final c*ck-up was missing out two capacitors, which meant the receiver didn't work at all. I'm glad I eventually managed to debug it without any help.

In all, I think I spent about 22-25 hours putting it together, but the end result is worth it.

The Elecraft K1 has a fantastic little receiver and a built in keyer and puts out around 7W if pushed. I have had a couple of QSOs with it so far and it is a very useable QRP radio.

I can thoroughly recommend it as a QRP project, although Elecraft have now moved on quite a way with the KX2 and KX3 - but then my K1 kit is 12 years old!

Tuesday, 19 July 2016

Operating QRP from Beeston Bump (TG14) in North Norfolk

Update: YouTube video now available

Jim G3YLA and I operated HF and VHF QRP from the top of Beeston Bump in Norfolk as planned today.

It turned out to be the hottest day of the year, so not exactly ideal. Nevertheless, after parking up and walking to the top we were met by a fantastic 360 degree view.

I quickly set up by 40m inverted L end fed half wave (EFHW) on a 10m fishing pole, bungeed to a bench and fed it with my homebrew EFHW matching unit, while Jim tried some CW on 2m from a little beam. He didn't get anywhere with that so switched to FM and had a quick chat with some locals on 145.275MHz.

Once the HF antenna was erected I handed Jim the coax and he set to on 40m CW and quickly worked a station in Germany using 2.5W from his Yaesu FT-817.

Jim G3YLA working Germany on 40m CW.
I meanwhile tried to see what I could work on 2m FM and could raise the GB3FR repeater across the water in Spilsby, Lincolnshire, but there was no one on it. I switched to GB3NB in Norfolk and worked John G8VPE.

I then took over on HF, but 40m was hard work and 20m was not much better. I eventually went back to 40m CW using my 2.5W Steve Weber-designed Mountain Topper Radio (MTR) and raised fellow G-QRP club member Peter G3XJS near Wrotham, Kent who was using 5W to a doublet. I was very pleased to make the contact as that was the first time the MTR has been used in the field.

Looking at the Chilton Digisonde data I think this was via Sporadic E (Es) on 40m as the F2 critical frequency was only about 5MHz - we don't normally associate Es with 40m, but you could see the Es on the plot.

Jim G3YLA then took over again using his FT-817 and had a long CW QSO on 40m with a station in the Netherlands. 

The information board for the Y station.
There were a lot of walkers on the hill and we were able to explain what we were doing - it was quite apt as this was the location for the Beeston Hill Y Station, a secret listening post during World War Two. The chain of Y stations were on the front line, feeding Enigma intercepts to the War Office’s Bletchley Park.

There is an information board all about the Y station and the concrete foundations are still there.

Propagation was iffy at best and the heat was getting to us, so we decided to take the station down and head for the nearest pub for fish and chips and cold refreshments.

My home-made EFHW matcher and SWR
 indicator.
All in a great day and we both agreed we'll go back, perhaps in late September when propagation is better and the temperature is a bit more reasonable.

I also shot some video and I'll try and edit that over the next few days.
My three-band (40, 30 and 20m) Mountain Topper Radio.
3W CW on 40m raised Peter G3XJS in Kent.

Update:

I thought I would do a Reverse Beacon Network (RBN) check tonight.

I was pleasantly surprised to see I was picked up all over the place, including the US, from the top of the bump.

Jim G3YLA wasn't for some reason - not sure why as his CW is waaaay better than mine. Perhaps it was because he responded to CQs and didn't call CQ himself.

Reverse Beacon Network captures from the day -
chuffed I was picked up in the US (just) with 2.5W to an EFHW for 40m (click to enlarge).
Update: YouTube video now available

Saturday, 16 July 2016

G0KYA to operate a "BOTA" station - "Bumps on the Air"

Beeston Hill near Sheringham in North Norfolk.
Image Wikimedia/Stavros1
I plan to operate QRP from Beeston Hill in North Norfolk on Tuesday 19th July as part of a new "BOTA" activation.

BOTA stands for "Bumps on the Air" a wholly-fictitious new organisation for radio amateurs who don't have access to real summits and mountains.

Beeston Hill (known locally as 'Beeston Bump') is not the highest point in Norfolk, but at 63m (207ft) above mean sea level it offers a good view of the coast and excellent HF take off.

I wanted to have some outdoor local QRP SOTA fun, but Norfolk is a little short of suitable summits (well, none actually) and Beeston Bump will have to do.

The highest point in Norfolk is nearby Beacon Hill at 103m (338ft), but I don't want to overstretch myself! Anyway, the view is better at Beeston and there are more ice cream shops nearby.

I've been meaning to do this for years!

Beeston Hill Y station circa 1940.
Image; Wikipedia.
I plan to operate 40m and 20m QRP CW using one or more of a variety of commercial and kit-built radios, including a Yaesu FT-817, Elecraft K1, Mountain Topper Radio (MTR) by Steve Weber KD1JV and a 1W Rockmite. Antennas will be end-fed half wave (EFHW) dipoles.

Beeston Bump is no stranger to Morse code. Beeston Hill Y Station was a secret listening post located on the summit during World War Two. The chain of Y stations were on the front line, feeding Enigma intercepts to the War Office’s Bletchley Park.

There are no awards for working me on Beeston Bump, no certificates and no special QSL cards - just my normal one. And just the fun of working CW at about 16-20 wpm around the usual QRP watering holes on 20 and 40m. I hope to be there from about 10:30am.

Jim G3YLA, a fellow QRP enthusiast, might be with me too.

(With apologies to the excellent Summits on the Air (SOTA) organisation!)

Friday, 27 May 2016

Updated UK HF prediction charts

I've now updated my hourly UK HF Propagation Predictions maps for the rest of 2016.

You can view the charts using the link on the right or at infotechcomms.net/propcharts/

These take into account the latest smoothed sunspot numbers from NOAA/NGDC.

We continue to see a steady decline in sunspot activity as we fall away from the peak of solar cycle 24. Twelve months ago the solar flux index peaked at 163 in May. This month it has struggled to exceed 100 and is currently 94.

Coupled with this, we have suffered quite badly from the effects of plasma from solar coronal holes. These are areas of the sun with an open magnetic field that allows plasma to escape.

If these coronal holes are earth-facing the result can be an elevated K index as the plasma from the high-speed solar wind stream impacts the earth, especially if it has a negative or south-facing magnetic field, which couples more easily.

A high K index is usually a sign of poor HF conditions, with noisy bands and depressed maximum usable frequencies. Any path over the poles is also badly affected.

This can also lead to aurora, which while not being visible in the summer, can lead to openings on VHF.

The RSGB Propagation Studies Committee is also pleased to be able to present its latest HF propagation prediction tool, which is currently hosted at www.predtest.uk

This is still being developed and uses the newer ITURHFPROP software as its backend, rather than VOACAP.

We encourage amateurs to use the system, which can also be used for point-to-point predictions using a prototype tool called 'Proppy'.

Gwyn G4FKH, who is project manager for the new system, welcomes feedback. The goal is for the whole system to be moved to the RSGB website once finished.

Thursday, 19 May 2016

Sporadic E season is under way

The Sporadic E (Es) season on 10m and 6m is well under way with lots of useful openings.

I was having a listen around 28MHz today and was struck by how many 10m beacons are audible when there doesn't appear to be any other activity on the band.

And they aren't high powered either. First I heard OK0EG on 28.2825MHz in the Czech Republic and a little late OY6BEC in the Faroes on 28.235MHz. Then a little later still I spotted a spike on the IC-756 Pro3's panadapter and it was F5ZWE near Toulouse on 28.2427MHz.

You can get a current list of 10m beacons, complied by Martin G3USF, at: http://www.keele.ac.uk/depts/por/28.htm

These are all running 10-15W and simple antennas, yet can reach S6-9 in the UK when the conditions are right.

We still don't completely understand Sporadic E, although the current thinking is that it is due to wind shear in the upper atmosphere that pushes ions together into clumps or clouds. The ions may come from meteors. Jim G3YLA, who is a professional meteorologist, is also looking at whether these winds, when they pass over mountain ranges, are forced upwards and create these "gravity waves" that force the ions together.

I also have a theory that solar flares can contribute to SOME of the ionisation on occasions, but mainly outside of the May-August period - there are plenty of instances of Es without any flare activity. I have some plots of Es in late April that correlate very well with solar flares.

Anyway, Jim posts some daily high-level wind charts in an attempt to understand what is happening. 


Steve G0KYA