Re: new tubes

• To: tesla-at-pupman-dot-com
• Subject: Re: new tubes
• From: FutureT-at-aol-dot-com (by way of "Terry Fritz (moderator)" <twf-at-verinet-dot-com>)
• Date: Fri, 04 Dec 1998 11:13:55 -0700
• Approved: twf-at-verinet-dot-com

In a message dated 98-12-04 01:22:56 EST, you write:

<< My question is: He mentioned seeing 803's in a push-pull circuit being run
> at 2000W, but I only show the max plate disipation as 125W.  He says its
> possible, but they glow red hot.
 
> Comments?
 
> Ben Bouxsein
  >>

Ben,

Class C operation can give an output power that's a lot higher than
the plate dissipation rating without stressing the tube.  Another secret
to obtaining high power from a small tube is to run it at a higher
than rated plate voltage.  Also, the 803 with its graphite plate can
generally handle a lot more power than than its rated for, for short
periods of time.  In one TC
design, I used (4) 845 tubes (similar plate structure to the 803), and
obtained 26" sparks using about 5000 watts from the wallplug.  This
design was very inefficient, but my peak input voltage was 6kV.  The
tube is rated at 1200 volts.  In a later design, I used one 845, applied
3500 volts rms, and obtained a 20" spark.  The plate did redden a little 
after awhile.  The 803, being a pentode, might not be able to handle
overvoltages as well as a triode.

John Freau

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