Fwd: [AMPS] Filament protection.

[Marv Gonsior]

>G3JVC wrote:

>Would it be considered good practice to put a small variac in the primary 
>circuit of
>the filament transformer, supplying a transmitting tube, and run the applied
>voltage up slowly, thus allowing the filament current to be more controlled,
>during that destructive switch on surge..
It sure would do the job, John, but an automatic means to accomplish the 
same thing would be the use of a Keystone Carbon Co.'s NTC (negative 
temperature coefficient) thermister.  It will slow ramp up the voltage and 
you won't have a variac to contend with plus its size, cost and weight are 
much less.  GL!

73,

Marv, W6FR




--
FAQ on WWW:               http://www.contesting.com/FAQ/amps
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com