>> Has anyone hacked the Alpha circuit that would sense the
>> duration of
> filament voltage loss and change the timer accordingly?
I ran into the same thing so many times I changed my timer
in a homebrew amp to a ramped reset. I use a different
current in the reset path of my timer, so the capacitor
To be safe with my tube, I have a full warm-up reset after
1/3 of the time Eimac requires for the warm-up time.
To be more exact, I use an op-amp comparator. The warm-up
time is 5 minutes as a capacitor charges from zero to 66% of
supply voltage. The pull down circuit is constant current
discharge and takes the capacitor down to zero volts in 100
seconds. In 50 seconds it takes about 2-1/2 minutes for a
reset. In 25 seconds only about one minute or so. In 5
seconds off it takes 10-15 seconds.
You might do something like that. The key is to be sure the
tube is at rated CATHODE temperature before reset, and you
can't measure that externally. You have to time safely.
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