[Amps] Henry 2K-4 Failure

[Mark - N5OT]

Thanks ALL!

I'll swap in a different set of tubes to confirm or rule out that it's 
one of the tubes.  Then if it is a tube, I'll do them one at time to 
figure out which tube it is.

Thanks for all the great answers.  A bunch of "it's probably a tube" 
then a couple outlier answers for if it turns out to not be a tube :-)

73 - Mark N5OT


On 3/18/2020 10:33 AM, Mark - N5OT wrote:
> Hello [Amps] Gurus,
>
> I had a failure of my Henry 2K-4.  I am betting it is a well-known 
> failure mode, and that multiple people on here, after hearing a 
> description of what happened, will be able to tell me what happened.
>
> I am operating a contest.  SSB.  I notice there is no output on my 
> power meter.  I look at the amp.  The meters are not moving when I 
> talk.  But the tubes are glowing orange quite nicely.  Like ... TOO 
> nicely.
>
> The tubes are glowing so bright orange - I know something is VERY 
> wrong.  I wasn't transmitting.  I could not make it stop.  I pulled 
> the TR relay control cable.  No change.  Nothing I tried got this 
> situation to change.  I shut off the amp's power switch and let 
> everything cool down (a very bad feeling to turn off both the glowing 
> tubes and the blower too - ugh).
>
> At that time, with zero drive, not in transmit mode, not key down, the 
> meters read like this:
>
> Plate current = 400ma
> Grid current = pinned negative
>
> I messed with the power switch and the breaker and the relay and the 
> bandswitch and - honestly I was baffled and not being methodical at 
> all - and after some "messing" the amp started working again.
>
> Then a short time later it happened again, but since I was keeping a 
> very close eye on it, I shut it off immediately.
>
> Then it started working again.
>
> Then finally it failed again and it has stayed failed.
>
> So ... my guess is, youall having a very large amount of knowledge and 
> experience, you can probably tell me which relay has failed or which 
> capacitor or resistor became intermittent then failed. Or if it's a 
> tube that shorted or something like that.
>
> Thanks in advance.
>
> Mark N5OT
>
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