Re: [Amps] vacuum relay failure

[Pete Smith <n4zr@contesting.com>]

Interesting.  Thanks, Vic.

I know it was the output relay because the grid and plate meters on the amp 
were still swinging -- in fact, probably over-swinging because of the 
unloaded state.  I had an arc or two when that happened.  Then when the 
input side decide to go, I was no longer showing any swings in either plate 
or grid current.  Didn't notice anything on the receive side, so far as I 
recall.

I have a spare set of contacts for the HC-1 on the output, so all I need is 
the inpout relay, and a couple of those are on the way from Allen Bond at MGS.

73, Pete

At 11:36 AM 11/22/2004, Vic Rosenthal wrote:

> Pete Smith wrote:
>
> > I have replacement relays on the way, but would like to tap the 
> > experience on the list -- does this sound like just contact failure, or 
> > might there be something else in play?  Is it logical to consider a 
> > possible causal relationship between the output and input relay failures, 
> > or just coincidence?  I should mention that the Hi-G is only rated at 75 
> > watts CCS, so it probably doesn't have too much headroom for a typical 
> > 100-watt driving signal.
>
> How do you know that the input relay wasn't the one that was failing in 
> the first place?  If either relay fails, you get no output.
>
> I would expect that if the output relay failed, the SWR seen at the input 
> to the amp would increase, since the amp would not be properly loaded 
> (understatement).  So that might damage the input relay.
>
> For what it's worth the vacuum QSK relay failures (Kilovac HC-1 or 
> Jennings equivalent) that I have have first manifested themselves as loss 
> of received signal.
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco

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