Re: Vacume tube TC

Tesla List wrote:
> >From DavidF4797-at-aol-dot-com Sun Dec  8 12:00:28 1996
> Date: Sun, 8 Dec 1996 09:46:18 -0500
> From: DavidF4797-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Vacume tube TC
> I've been tinkering around with a vaccume tube coil now for several months
> using a pair of 811a's (triodes) and was able to produce a nice 3" brush
> discharge off the top of the coil ( tall thin candlestick variety).  I then
> switched to a 4-500z with the intent to produce greater output....
> Unfortuneately, the same circuit doesn't produce *any* brush output, although
> if I get a flourescent tube near to the primary and secondary it lights up so
> there must be output of a sort.  I have heard it speculated that the extra
> controll grid in the 4-500z is causing the problem and that what I really
> need is a 3-500z triode.
> Does anyone have any ideas or suggestion about this?

	I was quite active in Amateur Radio and used both the 3-400Z and 4-400A
made by Eimac.  They upgraded the 3-400Z to the 3-500Z and the same for
the 4-400A.  I still have some of the original applications bulletins
printed by Eimac demonstrating the tubes uses in 80-10 meter linears, of
which I have made four.  
	O.K., the reason for mentioning this is at one time I recall reading
where some Amateurs used the 4-400A(4-500Z for you) in a grounded grid
configuration simply by wiring both the control and screen grids
together.  Try this method in your circuit and see if a difference is
realized.  I never needed to try it because I had the right tubes for
the selected design.  I still have 3 or so of these tubes down in the
basement, I guess as dust collectors at this time.  Good Luck with your

Chuck Curran, WA9POU