Wednesday, 24 May 2017

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


Tuesday, 9 May 2017

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 

Monday, 24 April 2017

A portable multi-band End-Fed Half Wave (EFHW) antenna for 40-10m

The camping washing line spool used for the antenna wire.
A few people have asked about the 30m antenna Norfolk Amateur Radio Club used for its International Marconi Day (IMD) operations at Caister Lifeboat this year.

Ten Megahertz (30m) turned out to be a useful band for us, allowing CW contact after CW contact, despite poor conditions after a geomagnetic storm and a K index of five.

The antenna we used was a portable 40-10m multi-band end-fed half wave (EFHW) with a 49:1 Unun using an FT240-43 toroid.

It used a wire 9m vertically metres up a fishing pole and then about 5.8m out.

The novel thing was that I only built it the day before and it uses a Coghlan camping washing line spool with the string taken off and about 21m of wire wound onto it.

Caister Marconi radio station makes nearly 200 contacts



Right: Rodney G0CBO and Kim G4WUG contact another other 
radio amateur with Morse code from GB0CMS at 
Caister Lifeboat on International Marconi Day.





















Members of the Norfolk Amateur Radio Club (NARC) managed to contact 193 other radio amateurs in 31 different countries on Saturday 22nd April 2017 when they took part in the annual International Marconi Day at the Caister Lifeboat Visitor Centre to mark the inventor's birthday.

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

Notable contacts were with other special Marconi stations in the UK, Italy, and Ireland.

NARC 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.

On Saturday, the closest to Guglielmo Marconi's birthday, stations around the world are set up at sites with historical links to the inventor's work. These include Poldhu in England; Cape Cod Massachusetts; Glace Bay, Nova Scotia; Villa Griffone, Bologna, Italy and many others.

Visitors to the station including many other local radio amateurs and members of the public.

Steve G0KYA, who organised the event, said: “Conditions weren’t brilliant due to the effects of a solar coronal hole, but we started off by talking to Ian VK3MO, an amateur near Melbourne, Australia on SSB.

“We then went on to make contacts with other radio enthusiasts all over Europe and as far as North Carolina, USA using speech, PSK and Morse code.

“New this year was CW operation on 30m, which proved very effective with long runs into Europe using a new prototype end fed half wave antenna (EFHW). We also had the club IC-7300 running on 40m, which worked well but highlighted a few things we need to check, such as the overload light flashing when the other station was on 30m and we tried to work on 20m.”

“My thanks to everyone who helped on the day and to to Caister Lifeboat for letting us set up the station.”

The equipment used was 100W from an Icom IC-756 Pro3 (30/20m) and Icom IC-7300 (40m). Antennas were a W5GI dipole on 40m and G0KYA's monoband end-fed half-wave verticals for HF.

Thursday, 6 April 2017

International Marconi Day, April 22 2017


Saturday 22nd April 2017 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 15 award stations and send in a log extract - you don't need QSL cards.

I shall be helping to run GB0CMS again this year at Caister Lifeboat in Norfolk, UK.

There is short video that looks at the equipment the club used to make 165 contacts in 24 countries on Saturday 30 April 2011. And another for the 2012 event when we made more than 500 contacts.

See http://www.youtube.com/watch?v=Z41FLKaT7eY and
http://www.youtube.com/watch?v=C8ZRW0q6SyI

To help UK stations work the requisite number of IMD stations I have prepared some HF propagation predictions. You can view these online.

You can find out more about IMD at: http://gx4crc.com/gb4imd/

Wednesday, 29 March 2017

You never know who you might hear on HF!

Colonel Doug Wheelock, KF5BOC
I was tuning around HF today and heard an American accent on 14.275MHz. This was odd as conditions had been really bad because of a geomagnetic storm, complete with a K index of six.

I didn't think there would be much propagation to the US.

Listening carefully it turned out to be Keith RA/WD9GET in Star City, Russia. Keith is a flight surgeon with NASA and was operating the amateur radio station at the cosmonaut/astronaut training centre in Russia.

Before I had a chance to call him he said he was taking a break. That was a shame, but I left the rig running on 14.275.

Ten minutes later RA/KF5BOC came up on the frequency and was calling, so I replied. He was a good 59 on my 40-10m EFHW antenna at about 25feet.

It turned out to be Colonel Doug Wheelock KF5BOC, the International Space Station commander, who is in Russia at the Gagarin Space Centre to help with training. Blow me down!

So Doug and I were able to have a quick chat and I mentioned how I had been involved in the ISS schools contact with UK ESA astronaut Tim Peake. When we finished the pile-up started - big time!

Just shows you never know what you going to come across on HF.

Friday, 27 January 2017

A shortened multi-band End-Fed Half Wave (EFHW) antenna for 80-10m

The 80-10m EFHW
This is a shortened multiband antenna, about 23m long, for 80m-10m that offers low SWR (1.3:1) on 80m and 40m, and below 3:1 on 20, 15 and 10m. The antenna has almost 300kHz bandwidth on 80m between 3:1 SWR points. But performance is down about 8-12db on a dipole on 80m.

This design came from attempts to find an 80m antenna that could fit into a small space. This was because Norfolk Amateur Radio Club likes to take part in the 80m Club Championship (we won in 2016), but many members don't have enough space for a full size (132ft) dipole or the 100-102 feet needed for a G5RV or W5GI antenna.

This antenna lets you get on to 80m in a horizontal distance of about 12m (40ft) when used as an inverted sloper with the apex at 8m, although you'll be down a couple of S points on a dipole. But if the other station is 59+20dB, you'll be about 59 +5 or 10db, so all is not lost!

I take little credit for this as it was outlined in PD7MAA's and IK0IXI's blogs after extensive work on the antenna in the Netherlands. However, there was little on their blogs in terms of its performance or SWR characteristics. Hence this write-up.


Download the 80-10m EFHW antenna guide

Update 29/1/17:
I've updated the guide to look at replacing the coil with a 7MHz trap and also putting the antenna up as an inverted V.  The trap and about 14.2m of insulated wire would improve the 80m performance a little, if you have the space, but possibly at the cost of the 14MHz performance. Surprisingly the MMANA-GAL model suggests the inverted V would be worse for 80m NVIS communication.

Update 09/02/17
I thought I would bite the bullet and took the wire and loading coil off and replaced it with about 130ft of insulated wire. This needs some final tuning, but gives a low SWR across 80 and 40m, and SWRs below 3:1 across the higher bands. The last 20-25 feet had to run along a wooden fence. Performance on 80m was equal to or down 1-2 S pts on the W5GI. Performance on 40m was down quite a bit, perhaps 2-3 S pts.

It appeared to be directional compared with the W5GI (which was at right angles). Equal performance on 20m to Tunisia.

So the performance on 80m was marginally better than the shortened version, but the 40m performance was worse. This was confirmed with WPSR tests. The performance on 20m was roughly similar. The bands higher than 20m were mostly closed during the test.

I think the compromise position of the 132ft wire didn't help the antenna's performance and I think that overall, the 66ft and loading coil version was better on 40m an higher.. If you could get the whole wire in the clear you might better results.