[Drake] 3-500Z red by itself???

[richard radke]

Dave, had the same problem in my L4B a few years ago. One tube was cheery red and neg. grid current. There’s a new 3-500 in your future. Been working perfect ever since.

Rick
W9WS


On Jun 29, 2014, at 7:14 AM, Dave Edwards <kd2e at comcast.net> wrote:

> Several months ago, my Drake L75 had an issue where as soon as I transmit, the .5 ohm (or whatever it is) protection resistor would go POW.
> 
> I had another 3-500Z tube that has been sitting on a shelf for probably 15 years!!  (condition unknown)
> 
> Tried it, and problem solved. Full output, no fireworks!
> 
> I tried the amp yesterday, full output, but after 5 minutes or so...even on receive...the grid current meter would go negative, and after a minute or so, the tube would slowly turn cherry-red, the fan goes to high speed.  So I shut it off.
> 
> Turn on again after several minutes...same scenario.
> 
> Time for a new tube from this century????
> 
> Thanks for your thoughts!
> 
> By the way...awful quiet list lately!
> 
> ....Dave
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