[Top] [All Lists]

[Amps] FL-2100B input swr problem

Subject: [Amps] FL-2100B input swr problem
From: Eric Dobrowansky <>
Date: Fri, 30 Jun 2017 01:55:45 -0400
List-post: <>
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!



Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>