Re: Tuning problem

In a message dated 99-07-19 06:07:03 EDT, you write:

<< Hi all,
> I have just gotten some Al air-con duct for my new toroid, about 30cm in 
> diameter and 3 meters long. Since I'm using it I am unable to tune my TC to 
> get more than 3cm sparks.

> One thing I have noticed though is the more topload I add the more turns I 
> need to use on the primary? Does this sound right (isn't it supposed to be 
> the other way around?)?


This is normal.  A larger toroid will lower the freq, and demand more
primary turns.
>> Current TC specs:
> Primary: about 12 turns 1/4" refrigeration tubing (flat spiral).
> Secondary: 1050 turns of 0.5mm magnet wire, 5" diameter Acrylic tube
> RSG, 3100rpm, 4 electrodes

I don't like to use a non-sync rotary with NST's, it seems to destroy
the NST's and not give a very good output.  (I'm assuming your NST's are
similar to US ones).  You'll get more output at 100 bps (assuming that
S.A. uses a 50Hz power grid.)

> NST, 12KV, 30mA
> cap: 15KV, 0.02 microF pulse discharge capacitor

> Is it possible that my toroid is too big?

Yes, it does sound very large for the power input.  The largest toroid
I use with that size transformer is 5" by 20" alum duct toroid, but I obtain
the same spark length (42") when I use my 4" by 13" smooth spun 
aluminum toroid.  I also use a sync RSG running at 120bps, and either
a 0.0077uF, or a 0.0147uF cap.  (The larger cap stresses the NST less
voltage-wise).  Your cap size should be fine.

John Freau 
> Any help will be appriciated.
> H Buirski
> South Africa