Fair Snape Fell, G/SP-007, Sunday 13 March 2022
When I activated Wards Stone G/SP-003 with Matthew M5EVT at the end of January, I just couldn’t stop talking (sorry Matthew!). I don’t often get a chance to talk with a fellow radio amateur, especially one who is into home brewing. Somehow the subject cropped up about old CW rig designs and it transpired that both of us had thought about building an N6KR SST - Simple Superhet Transceiver. I had listened to the SolderSmoke podcast and heard Bill N2CQR talking about his SST-20 and I thought it would be a cool rig to try.
I had started buying components last year and added an SST on my list of things to build. Matthew set me a challenge, especially with the 20th Anniversary of SOTA happening, to build the SST by the time for our next joint activation, pencilled in for some time in early to mid March.
I started the SST-30 build almost straight away in the first days of February. I struggled to get the VXO working as it should, and then discovered that other builders had had the same problem. Eventually I got my VXO working by reducing the value of the capacitors in the oscillator circuit. I spent almost every spare moment throughout February building the SST. I was held back at times whilst waiting for obsolete parts to arrive via traders on ebay.
I had intended to finish the SST in time for the LD weekend on 5th/6th of March, but despite a late night on the Thursday before, I felt that the rig wasn’t working OK. I ran out of time, so I used my SW-20+ for the Lake District weekend, in celebration of 20 years of SOTA.
I ordered a piece of 4 inch wide brushed aluminium sheet and made up a case in style similar to the original SST. My case is a little bigger, I took the easy option and cut the 4 inch strip in half to give two 2 inch high front and back panels, the original SST is a bit smaller than this.
I thought I got the rig working this week and took it out up Pendle Hill on Thursday (see post above) however the audio was extremely low. I felt pretty disappointed with myself, I felt like a failure. Later that evening I sat in bed looking at the schematic and then I had an idea about what I might have done wrong. On Friday morning I raced in to the shack, once the kids were at school etc, and sure enough, my idea was correct - I’d soldered the audio amplifier IC gain set capacitor to the wrong pads! I reworked the circuit and then I found that I had much more audio gain and the cute little blinky LED on the front panel was now lighting up when sending, just as it should. The LED forms part of the AGC circuit and as the sidetone is actually the receiver receiving your TX signal, the AGC kicks in to reduce the audio level. I reckoned the rig was now sorted!
Matthew sent me a message yesterday saying that instead in our planned LD summit, should we switch to a more southerly summit where the forecast was better? I agreed and Fair Snape Fell was the chosen summit.
The drive from home to Fell Foot was really enjoyable, I’d had to get petrol so set off early and I found myself about 20 minutes ahead of schedule. I took my time whilst driving through the Forest of Bowland, taking in the scenery. So much wildlife about! Even though I was a bit early to the meeting point, Matthew arrived about 5 or 10 minutes later. As per last time, Matthew navigated whilst I quizzed him about technical issues!
The weather at the summit was nowhere near as bad as the forecast had lead us to believe, I didn’t even get my bothy bag out to sit on. I’d taken my SOTAbeams BandHopper 3 antenna as I didn’t want to bust my home brew dipole, the SOTAbeams one would be the sacrificial lamb in case of the predicted high winds. I was putting the antenna up when the croc clip for the 40m element fell off! Thank goodness I was using 30m!!
I fired up the SST aligning the VXO with a little dot I put on with sharpie pen, denoting 10.118MHZ. I could hear another SOTA activator on that frequency. Feeling a bit of time pressure, I decided not to try to work the activator for an S2S, instead I would move down the band a bit. From the RBN, I probably didn’t move down enough, I had ended up on 10.1175 MHz.
The rig was much better than before and QSOs were much easier although turning the AF gain up resulted in howling. Anyway, I worked 14 stations, including an S2S with Kurt HB9AFI on HB/VD-048.
I’ve just researched the SST howling problem on the Internet and it seems as though it’s a known problem right from the start. Thankfully there are some suggested fixes to try. It turns out that my SST is such a faithful tribute to the original, it has the original bad habits too! I think I will end up adding a Keyer chip, as my straight keying is pretty tortuous for chasers! I did want the true SST experience before adding any mods.
So I guess I just about met Matthew’s challenge, I did build the rig, and I did qualify a summit during our joint activation with it! Oh, by the way, the power output is about 1.5w from a 12v supply. Today I ran from a 3S lipo.
Colin