First darkness :-(

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <yinzara-at-mit.edu>

Well I finally got to testing the coil for the first time this evening.  With
probably the most disappointing results ever.  Nothing! Well the spark gap
fired continuously but I got nothing on the toroid. Even after removing the
toroid and retuning (well gueesstimating) I didn't even get a 1" 
streamer.  I'm
not quite sure what's wrong. Probably a combination of many things.

First of all, my ground doesn't seem to be functioning.  I drove 4 2" 
pieces of
3/4" copper pipe into the ground so only about 3" were showing. I then
connected these in parallel. I didn't test them until afterwards but found 
when
I put a light connected to hot and to my newly created ground, I didn't even
get a dim glow. I didn't try to test the resistance but I would't doubt it's
quite high.  I don't know why those pipes aren't working. I would think 
they're
quite below the frost line (I live in Massachusetts so the ground is frozen
here).

Here are the spects of the coil:
variac 140V output at high
12/60 nst
greg filter
geek group cap (8 in series)
spark gap air blast one gap (probably one of the main problems)
primary, flat, 10" inner diameter 15.5 turns with .2" between turns
second external tap primary. 4 turns with 1.5" between turns 18" diameter helix
(I tried bypassing the external tap primary as well as using all of it)
secondary, 4.25" outer diameter, 28awg magnet wire. 22"
Toroid, 6" dryer pipe, 29" outer diameter
Tuned with toroid secondary resonates at 120kHz
Primary resonates without second tuner at 120kHz as well
(both tested with oscilloscope)


I think my first problem is a coupling problem between the primary and the
secondary. I've got over 4" from inner turn primary to bottom of first turn
secondary and I think the coupling factor is completely off. Unfortunately I
don't have anything to measure inductance at my house so I'd have to bring it
to MIT's circuitry lab to test it and it's quite a hassle.  I think a good
solution might be to make some more windings for the inside of the primary and
just solder the end of it to the current primary so I reduce the distance to
the secondary at the same time as lowering the resonate frequency of the
primary so it's a bit below the secondary to make up for the difference caused
by the ion cloud.

I also think my air blast gap probably isn't very sufficient. I thought it
would be ok since I just wanted to get a preliminary test with it.  It's two
flat head screw driver bolts blasted with a fish tank air pump. Yes, you can
laugh, I know it's mostly useless but I just wanted to try it. I think next 
I'm
going to try a multi gap using 3/4" copper tubing. That seems the most
successful easy way.

A third and final problem that I see other than the ground is the toroid is a
bit oversized for that nst. It's just too big.  I have another capacitor bay
that I'm going to use for my next coil and I'll get another 12/60nst. That
should put out enough power for that toroid but unfortunately right now it's
just not very good.

I'd appreciate any comments anyone has about my problems and preposed 
solutions.

Sincerely,
Matthew Morrissette
MIT Department of Eletrical Engineering/Computer Science
Undergrad