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Re: Tube coils for beginers

> Date:          Thu, 23 Jan 1997 22:53:23 -0700
> From:          Tesla List <tesla-at-poodle.pupman-dot-com>
> To:            Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject:       Tube coils for beginers
> Reply-to:      tesla-at-pupman-dot-com

> Subscriber: dwt-at-efn-dot-org Thu Jan 23 22:40:10 1997
> Date: Thu, 23 Jan 1997 17:34:30 -0800
> From: David Trimmell <dwt-at-efn-dot-org>
> To: tesla-at-pupman-dot-com
> Subject: Tube coils for beginers
> 
> Hello,
> 
> I have built many standard Tesla coils and resonators, but with all this
> talk of tube coils, I believe that would be a worthwile project. So, I
> am sending out a plea for help. Could one of you kind people with tubing
> expierience assist me? I need a simple beginers cookbook guide. I may be
> able to aquire a couple of 833A's, not sure yet, but I could get some
> 811's for sure, what other types of tubes should I look for? The
> microwave transformer shouldn't be to hard to get, what else do I need?
> What capacitance value is generally used? can't imagine it'd be much
> different from a standard TC tank? Any help would be apreciated.
> 
> Thanks in advance,
> 
> David Trimmell <dwt-at-efn-dot-org>
> 
David,

810 tubes work great if you can find them.   The tank circuit in a 
vac tube TC employs a proportionately larger L and smaller C at Fres 
than a traditional disruptive discharge TC, because the capacitor 
doesn't have to store the bang size in the same way as in a 
disruptor, and the extra L is required to better match the impedance 
of the vacuum tube(s) employed.  Primaries of 20-30 turns are common 
with capacitance sizes of as low as 300 pF.  A variable, aluminum 
finned "cheese slicer" transmitter tuning capacitor rated at 6000+ 
volts can be the entire tank circuit capacitance with good results.  
Primaries are best wound as cylindrical solenoids.  I like to put the 
grid feedback 'tickler' winding below the plate tank coil, nearest 
the chassis.  Vacuum tube coils are one place where long candlestick 
designed secondaries, tightly coupled to solenoidal primaries work 
O.K.  If you require it, I'd be happy to snail-mail you a xerox copy of an 
article from a '60's Popular Electronics article describing such a 
coil system employing a pair of 811A's.  Contact me off list with 
your mailing address if you wish.  Please allow 6-8 weeks for 
delivery.  All major Credit cards accepted. (just kidding) : )

rwstephens