[Amps] Input SWR

[Russ Williams]

I am not familiar with that particular amp, but it sounds like something was either damaged when the old tubes failed -or- something has changed during or since the new tubes were installed.  
I doubt the tubes would be the culprit since I have installed and used the RFP 3-500Z's with no problems in an L-4B.  (That is not to say they couldn't be the problem)

It is obviously a common component to all bands, so I would look at the following:

1. Check the coupling capacitors that feed RF to the filament (cathode) at the socket.  These may be leaky (electrically) and are changing value.
2. Check other components common to the input circuit on all bands; e.g., T/R relay, bandswitch, other capacitors, etc.
3.  Unlikey to be the problem, but does the tube socket grip the tube pins sufficiently, and is the socket clean?  

Any other ideas out there?

Russ
W6OHM


--- On Tue, 12/9/08, Robert Perdue <kc0hfl at cox.net> wrote:

> From: Robert Perdue <kc0hfl at cox.net>
> Subject: [Amps] Input SWR
> To: Amps at contesting.com
> Date: Tuesday, December 9, 2008, 7:00 AM
> Hi all I hava Henry 2KD-5 That I recently installed a new
> set of tubes in they were purchased from RF parts. Now here
> is the problem after operating for a few keys the input swr
> climbs and folds back my radio after cooling the cycle
> starts again with a little use input swr climbs. Have any of
> you ever seen this with the 500-Z tubes and yes it happens
> on all bands.
> 
> Bob,kc0hfl
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