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[AMPS] Another Tube Max Plate Current Question

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Subject: [AMPS] Another Tube Max Plate Current Question
From: (2)
Date: Mon, 3 Sep 2001 20:31:03 -0700
>> This time about the 3CX800A7 Tube. What is the maximum allowable Plate
>> Current of a 3CX800A7 Tube ?? Can it be operated at 600 ma without
>> degradation or damage ??? 
>Tubes do not live happily for many years at 500mA, and then 
>suddenly die if you run 20% more current.
>As a matter of fact, current has little if any effect on life as long as 
>you don't exceed the peak emission current of a MOX cathode tube.
>With thoriated tungsten, like an 813, you can hammer the heck out 
>of the emission with no ill effects at all.
>3CX800's actually have a published IVS (intermittent voice service) 
>rating that exceeds the value in the typical operation tube tables. I 
>don't have that data handy, but you would certainly be fine at 20% 
>over normal ratings as long as you don't exceed the dissipation 
>rating of any elements and have the rated filament voltage applied.
>Excessively low heater voltage is the real enemy of MOX cathode 
>tubes being operated at the max.

//  However, too much heater potential causes barium to migrate from the 
cathode to the grid.  The limit is +/- 5%.  

-  R. L. Measures, 805.386.3734,AG6K,  

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