I am working on an FL-2100B amplifier which is exhibiting high input SWR on all
bands except 40m.
I went ahead and replaced all of the capacitors on the tuned input circuit with
new micas, including the 1000pf from the band switch to the tube socket. I also
replaced the two 200pf caps in the grid circuit of each tube.
SWR is still high on all the bands except 40m.20m will work somewhat, at about
a 3:1 SWR, but all the other bands are exhibiting a very high input, to the
point the exciter folds back hard.
I've even tried a spare set of tubes just for the heck of it. Every other
component I've checked on the input circuit is checking good at this point.
Is is possible that the 1000pf plate blocking/coupling doorknob cap could have
shifted value enough to cause such issues on the input side?That's about the
only thing left....all of the band switch contacts, both input and output,
check good.Unfortunately I don't have a 3kv cap on hand to try at the moment.
Searching the archives I see CO8LY posted the exact same symptoms a few years
ago. But I do not see any solution to his original post.
Any suggestions greatly appreciated!
Thanks.
Eric
K2CB
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|