[Amps] FL-2100B input swr problem

[Jim W7RY]

Yes and yes to the band switch being in sync.


"SWR thru amp when in standby is fine".  This has nothing to do with the SWR 
though the amplifier only when the amplifier is operating.

73
Jim W7RY


-----Original Message----- 
From: K2CB
Sent: Friday, June 30, 2017 6:55 AM
To: Jim W7RY
Cc: amps at contesting.com
Subject: Re: [Amps] FL-2100B input swr problem

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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