Re: 803's in a Tesla Coil

• To: tesla-at-pupman-dot-com
• Subject: Re: 803's in a Tesla Coil
• From: Ed Phillips <evp-at-pacbell-dot-net> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
• Date: Fri, 20 Nov 1998 16:27:51 -0700
• Approved: terryf-at-verinet-dot-com

Tesla List wrote:
> 
> Original Poster: "Benjamin W. Bouxsein" <bbouxse-at-comp.uark.edu>
> 
> Hello all,
> 
> Anyone ever tried an 803's in a tesla coil circuit?  I found the coolest
> TV repair shop in the world today, and the guy had just about every tube
> made except an 811A.  But, he did have about 4 803's new in boxes.
> 
> Does anyone know how to make these work for a Tesla coil?  Just dont
> connect the extra screens?
> 
> Ben Bouxsein

	The 803 is an old (circa 1940) RF pentode, rated at 125 watts plate
dissipation , which is about twice that of the 811A (65 watts in
intermittent duty). My RCA transmitting tube manual rates the 803 at 210
watts output in Class C oscillator service with a plate voltage of 2000,
screen-grid voltage of 150 volts, plate current of 160 ma.  This is with
a tetrode connection (grids 2 and 3 tied together).  So, one or more of
those should be equivalent to two or more 811A's.  Filament voltage is
10 and filament current is 5 amps.  Personally, I'd prefer a triode such
as the 211 or 805, but the 803's should work OK and think someone has
reported here about using them for a TC driver.

	Don't have any dandy oscillator circuits, but that shouldn't be much of
a problem.  Not sure what to use for the tank tuning capacitor.  Experts
please comment.

Ed

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