Wednesday, 30 October 2013

Two Tinned Tunas

I came away from the G-QRP convention with a number of goodies, including a Two Tinned Tunas EZ build kit. The kit comes as a pull top tuna can and a PCB.

Open the can to find the parts :-)

Follow the excellent step by step guide to build into a 350mW transmitter!

The kit worked first time and the step by step guide was excellent. My meter was showing around 400mW output on 7.030MHz from 13V supply. (The gold base does not come with the kit.)

It does what it says on the tin! :-)

Tuesday, 29 October 2013

2013 Rishworth G-QRP Convention

The annual G-QRP convention held at Rishworth School near to Halifax is the highlight of the amateur radio calendar for me. In 2011, it was no longer permitted to hold the usual 'Buildathon' in the school laboratories, so instead it was decided to hold the Buildathon at the Premier Inn, at Salterhebble not too far away, on the evening before the main event and thus turn the convention into a two day affair.

There seemed to be a very good atmosphere during that first Friday night construction evening, I took part in the construction myself and successfully completed a Manhattan style Z match ATU. I enjoyed building the project but I found that I rather missed out on the social activity.

This year the Friday night event seemed better than ever, all seemed to be enjoying the conversation and free buffet. I was very pleased to meet Rex, W1REX, for the first time. I have built a number of Rex's QRPme kits since buying my first SUPER Tuna ][ kit from G-QRP club sales at the 2011 convention. Rex had brought the original 1976 Tuna Tin 2 transmitter built by Doug Demaw, W1FB, with him from Maine. I spent most of the evening chatting with Rex about RockMites and Tuna can kits. George Dobbs G3RJV kindly signed my copy of his new QRP book. The Buildathon project this year was the RSGB centenary 20m PSK receiver, I heard that ten builds were attempted and all ten were working at the end of the night.

By 1130pm there were only four people left in the room, including myself; we decided to retire for the evening. Rex picked up his soldering ironing and headed off for his room to do a couple of hours of kit building, whilst I drove the 12 miles to my home QTH.

Saturday 26th October.

I left home at about 9am and stopped off at the convenience store to pick up some sandwiches and drinks for the day. The convention is famous for it's pie and peas, but as I'm vegetarian it's not much good for me! I managed to find a space on the main road outside the school not too far from the entrance, I got there about fifteen minutes before the 10am convention start time. The queue to get in had started to form but I was pleased to be reasonably near to the front.

Unlike previous years, the event opened pretty much exactly at 10am, in the past the doors seemed to be open earlier than this. I heard the usual reports that the traders had all looked at each other's stalls before the official opening and snapped up all the good stuff - I guess that's a perk of being a trader!

My first port of call was to find the book stall run by Richard G3UGF. I bumped into fellow SOTA enthuiast Mike, 2E0YYY whilst trying to locate the book stall. Eventually I spotted Richard at the other end of the hall and dropped off my donation of books, it was a relief as those books were heavy! The book stall had lots of stock and lots of them were interesting historic titles, including some copies of the famous 'Solid State Design for the Radio Amateur' (SSDRA) by Wes Hayward W7ZOI.

The lecture stream started at 11am, first up was a talk by Ian Keyser G3ROO about spy sets. Ian was also joined on the stage by Roy GM4VKI and Johnny Apell SM7UCZ and there were a number of radio sets to look at after the talk.

After Ian's talk it was time to head back to the main hall for lunch. Lots of people were enjoying the pie and peas, whilst I took the opportunity to have a look around the stalls whilst it was a little bit quieter. I bought a new G-QRP club mug as the one that I bought last year got smashed at work; a bargain at only £1! I also picked up a free bag of 2N3866 transistors, I need to find a suitable project now to use them!

The second talk, after lunch,  was by Paul Darlington M0XPD about using the Arduino and similar platforms as a basis for radio projects.. Paul's talk was very well delivered and quite inspiring. I came away thinking about having a play with an Arduino myself, so Paul's talk certainly worked on me! Paul's blog here -

The next talk was by Colin G3VTT. Colin's talk was about his adventures with AM broadcasting from ships at sea. The talk was very entertaining and a good insight in to the technical challenges of operating a high power radio system away from the comforts of land. I felt a little connection with the story as Colin described operating his Elecraft K1 from the Radio Seagull ship. Colin described how he used the Rishworth Buildathon ATU project as a 'sacrificial ATU' to protect his K1 from the AM transmitter. That particular ATU was built by his wife who was sat next to me when we built the kits together!

The rest of my afternoon was then spent chatting with friends and Rex on his QRPme stand. I got to see the original Tuna Tin transmitter again and pose for a photo with it.

Tuesday, 6 August 2013

MTR version2

I was lucky enough to secure another MTR (Mountain Top'er) kit from Steven Weber, this from his second batch released at the end of March 2013. I had been keeping an eagle eye on the AT Sprint Yahoo group for news of the release of another 149 MTR kits. I was amazed when an email came through just as I was getting up for work early one morning announcing that orders were being taken for the new run of MTRs. I ordered straight away but I was worried that I might have missed my chance to own another MTR as I worked out that it had taken 40 minutes for the original email to come through to my phone. I need not have worried though as I later learned that only twelve kits had been spoken for by the time I ordered.

My order confirmation came through pretty quickly from Steve, I was over the moon to have secured another MTR, this time with a neat custom case. The package arrived around 2 weeks after ordering, Steve stated that he had bought the entire stock of shipping boxes from his local Post Office and did not have enough to send out all the orders! My kit had been held back a while whilst Steve sourced some more boxes.

The kit was neatly sealed in plastic and the components were grouped together to make finding them a bit easier. Thankfully all the components were there with none missing. I think Steve does a great job with his kitting, it must be a nightmare with so many tiny components to count out. There were 149 kits made available this time around and just as with the last run, each kit was given a unique serial number, my kit being #267. The numbers for the second run started at #151, as they followed on from the last number of the first run kits.

 The board went together well, although it was time consuming; there are more components than you realise and you have to build on both sides of the board. The processor and DDS chips were mounted first of all and I had learnt from my experience with my first MTR, so this time the chips went on pretty smoothly. I followed the assembly sequence suggested by Steven, KD1JV.

 The build instructions had a few small mistakes, mostly due to the fact that the manual had been modified from the one for the first run kits. It didn't take much thinking to work things out though, the provided schematic helped out here. The obligatory PCB trace error had crept into the design just for a bit of interest,  so a small wire jumper from Q2 (top left) was needed. The ground pad for the antenna connector also needed modifying, it had been flagged as a via by mistake so the solder resist had to be scraped off with a sharp knife.The smoke test went well and soon I was ready to fit the final inductor (L14) for the PA and perform the alignment. The alignment firstly consists of putting the rig into calibration mode by powering up the board whilst pressing two front panel buttons. The rig then sets up a 10MHz signal from the DDS, this signal is measured using a frequency counter at the provided test point. Using the up and down buttons, the signal is calibrated to exactly 10MHz.

Once the reference oscillator is set, the BFO needs to adjusted, this is simply a case of measuring the audio output with an oscillscope and peaking the internally generated audio tone for maximum amplitude using a single trimmer capacitor (CT1).

All that is needed to be done after calibration and setting of the BFO is the align the RX band trimmers. I used my FT817 (my only commercial HF rig) to provide a signal to tune my SOTA dipole using a manual ATU. I tuned for 1:1 VSWR  at the radio and then swapped the FT817 for the MTR and peaked the two trimmers for the first band for maximum response. I then repeated the whole operation again for the second band.

The board had already been tried into the case in order to cut the wires to the correct length for attaching to the external sockets. Putting the PCB into the case was just a matter of disconnecting the power and antenna jacks, as these pass through the case from the outside, and then resoldering them when in the final positions. The board is held in place by  four screws through the top of the case and into the stand offs soldered into the PCB at each corner - a neat solution. A strip of felt across the four push buttons gives a tidy appearance along with the red transparent plastic window for the display.

The rig is very pleasing to use, I built my second MTR for 20m and 30m, and I find 30m is great for weekend SOTA when there is also a big contest on the bands. I like the new case, but I probably prefer my original Altoids tin MTR, it's so much more compact and lighter too! My Altoids tin MTR weighs in at 80g, whilst my new MTR with it's pretty case weighs in at 170g! There are some minor circuit board changes to the second run kits and it might be all in the mind but i find I prefer the audio of my first run MTR.

KD1JV has produced a great little kit that works very well. I'm sure these MTR's will be sought after for years to come. There are apparently 299 MTRs out in the wild and it's unclear whether there will be any more produced, Steven was making noises about making a more complex rig next time including DSP.

1% of the world's population of MTRs!


Sunday, 24 March 2013

SW-20+ Keyer speed control

After all this time I finally got around to fitting a CW speed control to the front panel of my SW-20+
This rig has been a 'work in progress' for a long time. I intended to use the rig for SOTA as my main 20m rig but then I managed to secure one of the limited run of KD1JV's Mountain Toppers (aka 'MTR'). I did manage to work a few contacts with the SW-20+ during testing, including a QSO with Bill, NG2D, in Pleasant Valley, New York.

I tried the rig out on one SOTA activation from Rombalds Moor G/NP-028, and the rig seemed to do OK, but I found that it was a bit tedious to change the speed of the keyer chip that I had fitted to the rig. I had used the PicoKeyer chip from Dale, N0XAS, and built a little Manhattan style keyer circuit fixed the the rear of the SW-20+ case. I had omitted the speed control potentiometer for simplicity, the speed can be set through the menu accessed by pressing the front panel button. I found that I wished that I had fitted the speed control.

During building and testing of the rig, I decided to tweak the tuning range to cover a larger portion of 20m rather than the standard 30 to 40kHz. There is a capacitor that sets the tuning range, I had changed the value to give me band coverage from 13.999 MHz to around 14.070 MHz, I found that the tuning was a little on the difficult side, a slight touch of the tuning knob and you would QSY a number of kHz. Whilst I was inside the rig to fit the speed control, I swapped out the capacitor that sets the tuning range, I now get around 37kHz of swing from about 14.026 to 14.063MHz, this should make the tuning a little easier. I noticed that a lot of the SOTA ops in NA tend to operate above 14.060 MHz, usually 14.061 or 14.062MHz, I thought it was important to have these frequencies covered, whilst still allowing as much tuning below 14.060 as possible.

I ordered the 50k potentiometer from Ebay one afternoon and the very next morning it arrived in the mail, it almost seemed as though the vendor had posted it before I had ordered it! Fitting the potentiometer took quite a bit of work, I had to remove the FreqMite (PIC based frequency counter) from it's front panel bracket first. I left the FreqMite hanging from it's wires and as to be expected I suppose, some of the wires broke off. I then had to remove the fixing screws for the main PCB and move the entire PCB sideways out of the enclosure because I had broken one of the cover fixing brackets, doh! Luckily there is just enough gap between the cover fixing brackets to squeeze the PCB through - good design or pure luck? :-) I repaired the cover fixing bracket and then I removed the sticker on the front panel that said 'SW-20+', of course the sticker had to bring some of the silver front panel paint didn't it?!

Drilling the hole for the potentiometer actually went very well, I managed it without damaging any more of the silver paint. The potentiometer was finally wiggled in to its hole after a bit of persuasion; one of the IC's on the main PCB was just in the wrong place and was fouling. The next task was to rebuild the rig; the main PCB was pushed back into it's correct position and screwed into place. Then all the broken wires had to be fixed to and from the FreqMite. The FreqMite would no longer fit in the same place as before; I had to move the board away from the front panel a little bit and make a bracket extension to support it.

I wired up the new speed control pot to the PicoKeyer board and then it was time for a test - the usual law states that all potentiometers will be wired up 'backwards' i.e. the speed will go from fast to slow, rather than the expected slow to fast. Upon powering up the rig, I was greeted by the usual '73' from the PicoKeyer and the usual babble from the FreqMite asking it's questions, I tried the speed control and I had actually wired it up correctly! How I managed that, I will never know!

Whilst the cover was off the rig, I gave it a re-alignment just to make sure it was properly set up. I found that I could squeeze 2 watts on transmit from a 12v supply, so I think that's pretty good. I backed the power down to 1.5w and left it set at that.

So now the rig is just about finished I reckon, there is not much more room left in the case for further additions. I gave the top cover a quick polish up with some car polish, it's now super shiny! I could do with touching up the silver paint sometime and putting some lettering over the speed control knob, just to finish the rig off.

I am determined that I will do a proper SOTA activation with this rig, it's too nice to just have stored away in some cupboard.

Well, that's it for now folks, my next blog entry will probably be about building an MTR from the second batch of 149 kits - yes, I managed to secure another one! :-)

Tuesday, 26 February 2013

Not much to report!

Sorry for not posting a new blog entry for quite some time, life is busy at the moment, but that is good I guess - I'm never bored!

I have not been doing much in the way of constructing gear recently, most of my 'radio' time has been spent activating summits for SOTA (Summits On The Air). My MTR continues to perform very well, it is a brilliant rig for SOTA. I hope to be able to secure another MTR kit when KD1JV makes them available again.

There is scope for a little bit of radio construction in the not too distant future, so I hope to be able to update my blog with progress.

Hope 2013 is going well for folks so far.

73, Colin, M0CGH