[Amps] Checking Filament Voltage

[Ron Youvan]

> ##  You can do the same with a small surplus  1-2 A  variac, provided you use the variac to
> bring the fil V up slowly each time.   If the variac was pre-set to correct fil V, then a simple toggle used
> to switch on,  dunno if the  small variac would have enough Z to limit fil inrush.   In that case,  you could add
> a simple step start...... or remember to turn the  variac down to zero  after the amp is shut off each time.

   I believe in this situation a huge rheostat would be better than a
variable transformer of any kind.  The rheostat would greatly reduce
the "in-rush surge current."  This will be much kinder to the filament
of the tube/s.
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.