Re: 6 MOT Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>

Hi Allan
Not too sure if your question is for Tim or myself but I can advise re my
coil.

I'm sure I'm actually quite a long way from optimised yet. It makes an
impressive display but for the power I'm running I don't think I'm
efficient.
I've tried a few configurations and I'm on the track to improve it still.
I'm currently using an 8" dia sec with 54" of 0.56mm wire with 6"x27"
toroid. This sec loaded is about 57kHz and interpreting recent postings re
the OLTC I suspect the Q of my sec may be a little low. My re try a 12"dia
space wound 54" with 19tpi

The big deal with MOT's I've decided is lots of Cp ie at least 120nF and
lots of bps ie at least 300 and probably more. Keeping lower bps with my
88nF MMC does offer the advantage of limiting the mains current while I
play. Recent runs with 6MOT's have a total I/P of about 25A at 230V. (I need
to check that figure but its no far off)

My coil is totally conventional in every way. A standard AC drive to a
primary of 1/4 refrigeration tube wound on 1/2" pitch with a simple SRSG or
a TCBOR static. I'd note that the TCBOR gap set wide still gives the loudest
biggest sparks compared with any SRSG configuration I've tried (due much
higher bps) but it suffers from surging current draw from the mains (and
lots more of it I might add). I inevitably drop a breaker when using the
static gap but before I do the beast is alway going very well at about 7'.
Despite this the smoothness and control of the SRSG is still my preference
and I'm going to optimise this element. A high bps ASRG also is worth a
thought (see Tims coil)

Some points which may be useful.
1) I've made great use of rigid foamed PVC (plaswood) in my construction. A
really wonderful plastic material which I think is under recognised by
coilers particularly as a primary support system. The pri sits on a 20mm
sheet and the 15deg supports are made from 10mm. This stuff has ideal
properties,its particularly light, strong, gluable, and easy to machine or
cut. And yes its really cheap as it's mostly air.
2) Modest inductive ballasting and PFC have been worthwhile for me.
3) MOT's have worked really well for me no insulation or heating issues to
date
Good lick and care
Rgds
Ted L in NZ

> Original poster: " <allanh-at-starband-dot-net>
>
> I'd like to know the specs of your coil, sounds like you have found a
sweet
> spot.
> allan
>