Re: microwave transformers

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: microwave transformers
From: Tesla List <tesla-at-stic-dot-net>
Date: Fri, 31 Oct 1997 08:07:28 -0600
Approved: tesla-at-stic-dot-net

From: 	Daryl P. Dacko[SMTP:mycrump-at-cris-dot-com]
Sent: 	Friday, October 31, 1997 6:41 AM
To: 	Tesla List
Subject: 	Re: microwave transformers

At 06:16 PM 10/30/97 -0600, you wrote:

>Anybody had  success using microwave transformers to drive a TC?
>I've got two identical units removed from 900w ovens.  I tested them
>with a Fluke meter and a 1:100 probe and measured the no-load
>secondary voltage at 2250vac.  It occurs to me that one of these
>would make an excellent plate supply for a vacuum tube coil.  They
>even have a filament supply winding.  I'm a novice coiler, but the
>next time I come across a cheap 833A triode I'm going to buy it & try
>it.  Anyhow, just for grins I wired the primaries in parallel and
>the secondaries in series (cores shorted together) and got 4600vac (I
>don't know where the extra 100v came from).
>
>4600vac doesn't seem like enough for a spark-excited coil.  A massive
>cap would be required to match the low secondary impedance.  Also, it
>seems like the heavy spark current would quickly eat even the most
>robust gap electrodes.  Anybody know how to make a workable
>spark-gap TC with these beasts?
>
>Greg

No problem, I've used 5 KV for years to drive coils, and I haven't 
seen really bad erosion on my gaps.

The nice thing about coiling is that almost anything can be pressed
into service, and it'll work. Perhaps not as well as properly sized
components, but they will work.

My last 5 KV coil threw two foot arcs that had to be seen to be
beleved !

I used a .025 Mf cap and used four gaps in each leg, each gap spaced
about half the thickness of a sheet of paper. A Richard Quick style
gap would work fine.

Secondary was 3 inches and wound with upteen turns of about #22 guage
wire scrounged from an old TV transformer.

Don't be put off with all the talk about matched this, and factory 
made this-and-that. In small scale coiling almost anything can be
made to work, given that you're willing to 'mess around' a bit to
find the sweet spot of the components you have - Experiment !

My father-in-law dubed it the 'Halloween Machine'...