# RE: Tube coil calculations

Hi Ben
Take a look at an old Radio Amateur Handbook. My 1957 as well as my 1978 book
contain all the info you need on the 803's. (Somewhat lengthy for our
list). Why are you
using tetrodes? If you want to get by cheap use 811A triodes in parallel.
They can take 1500 V
on the plate with 175ma plate current each. My "old faithful" experimental
coil uses three in parallel
1300 AC 500ma to a plate tuned Armstrong Oscillator. All mica caps. Corona
is 10" brilliant and will
cause severe RF burns. Corona can be suppressed with a top load sphere or
toroid, however, you must
re tune the tank circuit. The easiest way to tune(I have found) with tube
tank capacitance in small values until max output is achieved.If you have
a grid coil above the tank
coil, don't forget that the TC must resonate for the whole system to work.
Otherwise nothing happens
i.e.. no feedback to produce the CW output. Tube coils are very sensitive
to tuning.

Only draw arcs with a well grounded metal rod otherwise you may
notice the smell of burned flesh but no pain...not good.

If you want to bump up the voltage you can use 810 tubes (available new or
the best tesla tube available with out going to very high power Eimac's.
All triodes and they will make your life
easier. Hope this helps.
John

John W. Gudenas, Ph.D.
Department Chair of Computer Science and Mathematics
Aurora University, Aurora IL 60506
Office: 630-844-5539     Fax: 630-844-7830

-----Original Message-----
From:	Tesla List [SMTP:tesla-at-pupman-dot-com]
Sent:	Thursday, January 21, 1999 12:19 PM
To:	tesla-at-pupman-dot-com
Subject:	Tube coil calculations

Original Poster: "Benjamin W. Bouxsein" <bbouxse-at-comp.uark.edu>

Hello,

When designing a tube coil how do you calculate the grid tank circuit
coil, and capacitance?  I am looking to use a pair of 803's in a tesla
coil circuit, so to use its as a tetrode which grids do I tie together?

thanx
Ben Bouxsein

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