Re: Filament Issue

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Ed Phillips <evp-at-pacbell-dot-net> 

Tesla list wrote:
 >
 > Original poster: robert & june heidlebaugh <rheidlebaugh-at-desertgate-dot-com>
 >
 > Yes!.. Low heater voltage will always give low output. The filament heat
 > supplies the source of current to the tube. low heat low output.
 >     Robert   H
 > --
 >
 >  > From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > Date: Mon, 01 Dec 2003 08:03:34 -0700
 >  > To: tesla-at-pupman-dot-com
 >  > Subject: Filament Issue
 >  > Resent-From: tesla-at-pupman-dot-com
 >  > Resent-Date: Mon, 1 Dec 2003 08:10:04 -0700
 >  >
 >  > Original poster: "Jim Mitchell" <electrontube-at-sbcglobal-dot-net>
 >  >
 >  > Hi, I was testing the voltage to the filament on my 813 tube in my VTTC,
 >  > and I noticed that it was like 4v, when the 813 has a 10v filament!  I am
 >  > wondering, is this a bad thing?  The filament does get hot, and the VTTC
 >  > works, but it doesn't work optimum, could low heater voltage cause this?
 >  >
 >  > Regards - Jim Mitchell

	It's hard to believe you got ANY output at such a low filament
voltage!  Try to run at rated voltage (measured at the socket) and
you'll get much better performance; it you were able to get enough plate
current operating at such a low voltage would deteriorate the life of
the tube.  The 813 is a pretty small tube but can put out enough RF to
power a small coil.

Ed