[Amps] FL-2100B input swr problem

[K2CB]

Yes and yes to the band switch being in sync.  SWR thru amp when in standby is fine.  

The only thought I came up with overnight is that possibly the coax from the relay to the band switch may be compromised. I am going to bypass it with a replacement piece this morning and give that a try.

Eric
K2CB 


> On Jun 30, 2017, at 7:21 AM, Jim W7RY <jimw7ry at gmail.com> wrote:
> 
> Is the input and output band switch still synced? Is the bandswitch knob in sync with the front panel?
> 
> 73
> Jim  W7RY
> 
> 
> 
> -----Original Message----- From: Bruce Blain K1BG
> Sent: Friday, June 30, 2017 5:59 AM
> To: 'Eric Dobrowansky' ; amps at contesting.com
> Subject: Re: [Amps] FL-2100B input swr problem
> 
> Inspect EVERYTHING between the output of your exciter and the first
> components in the amplifier closely.  Test the coax to a dummy load.  Look
> at the SO-239 connector on the amplifier chassis.  Use an external SWR meter
> (ie, don't trust the one in your transceiver).  Eliminate EVERYTHING as a
> possibility.
> 
> Hope it works out.
> 
> Bruce, K1BG
> 
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Eric
> Dobrowansky
> Sent: Friday, June 30, 2017 1:56 AM
> To: amps at 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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