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Re: Some background info - compliled from manufacturers' design guidelines

Posted by dave slagle (M) on January 11, 2002 at 14:17:48

In Reply to: Some background info - compliled from manufacturers' design guidelines posted by mb-de on January 11, 2002 at 12:18:25:

very cool notes... thanks

iirc steve bench's reduced filament was indeed with a thoriated tube, i thought it interesting that i saw something similar wiht an idr (indirectly heated rectifier)

if we accept the possible loss of a tube with time by running the heater at say 50% in the application i am thinking of that may not be so bad.

i am looking to try a damper diode in the cathode of a 6C45, experience tells me i need -2.7V @ 30ma, and i am looking for a damper that does this at say 80-90% filament voltage... then i can add a 1 ohm pot in series with the filament which will give me an adjustment from say 50-110% on the filament voltage, this should allow me to easily bias up the tube to the current i want....

even if the tube fails, it will lose emission hence increasing the voltage drop, requiring a highe rfilament voltage, at some point the tube will just be out of the range of adjustability so you pitch it and put in another, at $2 a piece, its no big deal!!!

thats the idea on paper, i just have to get it implamented and see if and how the sonics change as the tube ages, and if the tubes do indeed die a horrible death....

my major motivation for this is that the diode should provide an effective soft start for my mercury vapor rectifiers, and save a lot of hassle with turnon! I already have the diode there in the B+ but i have to go through the hassle of shorting it out, in the cathode, thats no longer needed!

dave

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