Wow, especially on St. Patrick’s day I think it is appropriate to say ” ’tis a thing of beauty. “
Colin did a great job on his homebrew version of the SST transceiver. It looks like his is on 30 meters. I especially liked his description of the troubleshooting that followed the construction. the assist provided by AA7EE’s blog was especially cool, and demonstrates the long-lasting power of internet-shared tribal knowledge.
Colin wrote (on Facebook):
I was inspired by Bill and his adventure with the SST-20, so I started gathering a few parts last year to build a Manhattan SST. I did a joint SOTA activation with a fellow homebrewer ham at the end of January and we started talking about classic portable CW rigs, it turned out that we both had an SST build on our ‘list’. I was challenged to build the SST for the next joint SOTA activation!
It took a lot of effort and a few late nights but I did manage to produce a rig capable of making QSOs for a joint SOTA activation of Fair Snape Fell, G/SP-007. I’d done a solo activation of Pendle Hill G/SP-005 a few days before with the rig for a trial run and I discovered that the AF was very low. After some troubleshooting I noticed that I’d soldered the LM386 gain set capacitor to an incorrect pad. Doh! I fixed my error and the rig had much more gain.
I found that with the improved AF gain, the rig would squeal if the gain was turned up. I was ready to give up really, but after a cool off period, I began researching the issue and it turns out that it’s very common and indeed I found posts from 1997 about it! It seems as though my recreation was so faithful to the original, I’d included the original flaws too! I added in a 0.1uF cap and resistor connected to pin 5 of the AF amp chip as per the suggestion on Dave AA7EE’s blog and now the squealing has stopped.
I’d made 14 QSOs during the joint SOTA activation, so I considered my challenge to have been met! It’s been a bit of an epic build!
73, Colin, M1BUU
Very nice well done to you. DE HS0ZLQ, G0MIH.
Wow that’s very good. Well done. I’m having to put all my stuff into boxes so I can’t make anything at the moment but after I have settled in. I’m going to start building stuff again.