[Amps] Applying HV during Warmup

Harold B. Mandel ka1xo at juno.com
Fri Sep 17 13:03:19 EDT 2004


Sirs,

As a further point of reference to my previous posting in which the
question of when to apply HV to the anodes of ceramic triodes
led me to dig up the full poop sheet from EIMAC on the 
3CPX1500A7 triodes that are going into the amplifier
project here, and I quote:

"  CATHODE WARMUP/COOLDOWN TIME - 
        It is recommended that heater voltage be applied for a minimum
        of 3 minutes before anode voltage and drive voltage are applied,
        to allow for proper conditioning of the cathode surface. It is
also
        recommended that after all voltages are removed from the tube 
        that cooling air/oil be allowed to run for several minutes to
        allow for proper cooldown. "

My question still stands.

Why would a commercial amplifier manufacturer want to apply
HV to triode anodes before proper warmup, especially if they
are in the same Oxide Coated, unipotential cathode series as
a device that particularly admonishes the user against such
action?

Respectfully,

Hal Mandel
W4HBM

 


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