[Amps] Regulated filament current

[Steve Wright]

On 05/09/15 04:00,

nemo zilch <nemozilch at gmail.com>

  wrote:
>  My inclination is to adjust the current so that the
> voltage across the tube is 12.6 volts.  Does this seem like the correct
> thing to do?
>

I was looking at similar using a programmable switching supply.  Once
the tube warms up fully, the current will normally drop off - except in
your case it won't be doing that.  Also, if "other" undefined RF
conditions cause the heat in the tube to drop then I think you might
discover some uncharted territory the tube designers never imagined.

Constant current heat-up time will be longer than constant voltage as well.

Any it has to be asked, why?  Just simply cold-start the filament in the
traditional manner.  It's robust and inexpensive, and it doesn't provoke
the designers into adding another chapter to their do's and don'ts for
this device.


Steve