It,s been a long while since I updated this section mainly due to construction of a concrete wall in my garden taking up most of my spare time. I have now completed the transceiver and am working on the digital frequency display.
How did I get on with the final build and test ?,
Well the build went ok apart from as previously mentioned the problem of identifing the small capacitors which was finally solved by the Impedance bridge. The components were all a good fit on the PCB, the only slight snag being that the board was covered in some sort of varnish which needed a lot of heat to penetrate and I ended up using a 25W bolt instead of the 15W one I started with.
The testing certainly went a lot more smoothly than the review in the April issue issue of RADCOM done by Phil Davies although I did experience the same problem of wrong orientation of components but not on nearly the same scale and I recon my rework time would have been no more than 30 minutes.
I had only a couple of snags during the testing the first concerning the IC which switches between TX and RX in the bilateral IF stage (both TX and RX ports being held open at the same time ), however after studying the diag this was traced down to the coils of the TX, RX switching relays not being soldered, for some reason I had soldered the contacts but missed the coils.
After curing the above fault the RX part of the set burst into life and no further problems were experienced with the RX. The second snag was again of my own making, unadvertantly during setting up the TX the croc clip connecting the earth terminal of my scope to the board sprang off the PCB and as sods law would have it contacted the slave transistor to the voltage regulator, needless to say it expired immediately but a junk box substitute was quickly found and testing resumed
The receiver seems quite sensitive which surprised me as it only has one IF amplifying stage after the crystal filter and the TX is certainly pushing out the claimed 5W on both bands.
I have not so far tried out the TX on the air as I want to finish the display before getting down to using the set
pictured below is the working TXCVR but with the display about to be wired in
As can be seen the chassis is made from peices of PCB but of course it is up to the individual how its cased, however I like this minimalist approach as I think its what QRP is all about.
The final view shows the set viewed from the rear.
The next update will be an on air test and will be done when I finish the frequency display.