> This really smells like RF getting in somewhere, but I can't figure what > it's doing to the radio to begin to try and choke it off. All the audio > cables have chokes/shielding/beads/bypasses. Looking at the KPA-100 > schematic, it would seem that the only devices capable of that kind of a > current spike are the finals or the TR switch diodes, and I can't figure > how they would be turning on on the return-to-receive cycle. It seems > like some sort of stored energy being dissipated as the transmitter is > shut off. I'm leaning toward the SSB module since there is no problem > in CW mode ( I know, just stay on CW!!), but I can't make the connection > between the SSB module and the PA.. > Any ideas you folks can toss my way I'd appreciate. Since I didn't have > any problems in the initial construction, I didn't get to dig into the > schematics the way some of you have. I'm hoping someone can take all > these pieces and complete the puzzle. > tnx, > Ken K6MR Hi Ken,
You are certainly digging into this one ! Don't know if it may help, but as you are heading towards RF feedback thru the SSB module you might like to try a mod that I put in my K2. I was getting RF into the KSB2 on 40m despite good external decoupling. I added a 1mH RF choke in series with the input to U3 (pin 4) and a 0.001uF between pin 4 and ground. It got rid of the problem. Worth a try, and will do no harm. Let us know how you get on. 73 Stewart G3RXQ _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
