[Amps] Checking Filament Voltage

[John Lyles]

This is probably a bad idea, for tubes over a few hundred watts power 
rating. Most ceramic metal tubes require cooling under the base, and for 
a few minutes, might still overheat the cathode/heater. If it were me, I 
would talk to the manufacturer of the tube for their recommendations.

John
K5PRO

> Date: Sun, 19 Feb 2017 16:10:02 +0000 (UTC)
> From: Roger Parsons <ve3zi at yahoo.com>
> To: Amps <amps at contesting.com>
> Subject: [Amps] Checking Filament Voltage

 > I am busily making a replacement amplifier using a metal/ceramic 
filament tube.
 >
 > I would like to coarsely adjust the filament voltage before I install 
the blower. (The amp is built into an existing cabinet and the filament 
transformer is a fair way from the tube.) My question is: Is it 
permissible to run the tube with only filament voltage and no air for a 
short period? If so, what is a short period?
 >
 > Thanks

>
> Roger
>
> VE3ZI