Just guessing, but you may have had a plate-grid flashover, which blew the
plate meter and then damaged something in the grid/biasing circuit. Zener
or capacitor perhaps?
Victor 4X6GP
On Fri, Sep 6, 2024, 15:49 Mark - N5OT <r-emails@n5ot.com> wrote:
> Greetings.
>
> Today I have a 2K-2 that has developed a problem. For grins / out of
> curiosity, I thought I would see what I could get out of a pair of used
> Eimac Y-826s that had tested good some years ago. After I tested them I
> wrapped those tubes up and put them on the shelf waiting for the right
> moment.
>
> The amp ran fine for maybe 2 hours on CW at probably 25-50% duty cycle.
> I was surprised how much drive was needed - really the tubes performed
> no better than the 3-400Zs I took out and set to the side. Oh well.
>
> When I was doing some additional testing the following happened:
>
> 1. The little red breaker popped when I let up on the footswitch. So it
> happened during a non-key-down moment. I let up on the footswitch,
> heard the click, amp now did not transmit. Checked breaker - it was
> popped so I reset it. Amp now worked again but plate current meter no
> longer works. Yes, I know I should have protected it. I am assuming it
> was not protected. Oh well.
>
> 2. Amp transmits just as it did, however, now the tubes glow orange 100%
> of the time, even while idling at key-up.
>
> I am assuming this is not a sustainable condition, something changed or
> broke, and I need to not run it like this.
>
> I am also assuming there are multiple smart guys reading this who know
> from the description above what has happened and can guide me toward
> restoring the amp to operation.
>
> Learning by experience,
> 73 - Mark N5OT
>
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