[Amps] Problem with my Henry 2K-4A

[Paul Kraemer]

I've seen negative grid current on Drake amps when one of the filament 
bypass capacitors is leaky
Paul K0UYA

-----Original Message----- 
From: Stan Gammons
Sent: Tuesday, November 07, 2017 9:53 PM
To: amps at contesting.com
Subject: Re: [Amps] Problem with my Henry 2K-4A

Every time I've seen negative grid current it was due to a shorted
tube.  You might try taking one of the tubes out and seeing if you can
isolate it to a single tube.  I don't know what experience you have
working on amps, but just be aware there is lethal voltage in the amp.
Please exercise caution working on it.


73

Stan
KM4HQE


On 11/07/2017 06:52 PM, Mark Beckwith wrote:
> Greetings,
>
> I'm writing the [Amps] reflector in hopes that someone reading will be 
> able to diagnose my problem with confidence.  It seems like the Henry 
> 2K-4A is a pretty well-known amp.  I imagine the answer is here somewhere!
>
> Lately when I transmit, after a couple minutes, I hear a very quiet 
> "click" and the plate current swings positive by a little (150-300ma or 
> so, depending on whether the plate voltage switch is in "CW" or "SSB"), 
> the grid current goes negative, and the amp no longer transmits.  If I 
> leave it like this for a little while longer, the built in circuit breaker 
> trips.
>
> Initially, the circuit breaker would not trip, I would hear the tiny 
> "click" again and the unit would be restored to operation for a little 
> while longer, before failing again.  After an hour or so of this, it 
> stopped correcting itself and would only blow the breaker.
>
> If the amp was turned off and left to cool for a while, it would go back 
> to operating, but only for a few minutes until it failed again.
>
> This happened the same regardless of the position of the bandswitch.
>
> Now after a couple days of this, it seems to be permanently in the failed 
> mode.
>
> Does this sound familiar to anyone?
>
> Thanks in advance,
>
> 73 - Mark, N5OT
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