My 2100 would not tune on 20...the problem WAS one of the caps, that is
where I would have started as well.
You probably already know this but look for something that is common to all
the band's input circuit. Maybe the band switch connection, coax to relay,
relay to band switch. Has the input connector been compromised, how is the
wire from the input connector to the relay?
Good luck.
Ken
N4zed
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Eric
Dobrowansky
Sent: Friday, June 30, 2017 1:56 AM
To: amps@contesting.com
Subject: [Amps] FL-2100B input swr problem
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
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