TSG questions

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

Hey all, 

With all the talk about the STSGs, I have been pondering a few 
questions in my mind that I thought that I would share with the 
rest of you. 

First, I purchased one of the GM HEI ignition coils and crudely 
wired it thru a cheap fan dimmer in series with about 4 micro- 
wave capacitors paralleled for ~ 4 uFD. I get the highest output 
from the HEI coil when the dimmer is turned almost all the way 
down (sharper, lower duty cycled pulses, I assume is the reason 
for this). Anyway, I get consistant ~ 1/2" spark output from the 
HEI with this setup. As I turn the dimmer up the spark output of 
the dimmer gets smaller and smaller. Now, I understand that ad- 
justment of the dimmer adjusts the phasing of the HEI output 
which in turn would adjust the phasing of the triggering of the 
main tank circuit. 

Now, I know that you are supposed to set a 12 - 15 kV NST's 
main SG around 1/4", so I suppose the up to 1/2" output would 
be of a sufficient voltage to reliably trigger the main SG in this 
setup. But let's say that the main power transformer has enough 
output voltage that it can reliably breakdown a 1/2" gap on its 
own, without an external trigger. In this situation, I can't see 
where the trigger pulse from the HEI coil would contribute toward 
triggering a gap that's going to fire anyway. It seems that the 
triggering mechanism would become little more than window 
dressing in this situation. It would seem that the trigger voltage 
must exceed the main gap voltage to be a reliable triggering 
mechanism. Of course if you set the trigger electrode half-way 
between the main SG electrodes, then you would only need 
half the voltage to start the main SG, since once an ionized 
channel is established, the high currents of the main tank 
circuit will quickly surge through the ionized channel. Ok, I 
guess I answered my own question there?? Obviously, my 
STSG construction efforts haven't gotten much beyond the 
drawing board at this point :-) 

Finally, my coil is pole pig powered and it seems that one 
would have to employ monumental quenching/ heat sinking 
efforts in order to employ a STSG with power levels in the 
> 5 kVA range. I would think that it would get to point to 
where it would be simpler to build the standard RSG (synch 
or asynch) than to employ all of neccessary heat sinking. 
I haven't really heard from anyone out there that has tried the 
trigger gap at pole pig power levels yet and I was wondering 
if anyone had had any success with the STSG in high powered 
systems? I may consider trying to convert my asynch RSG 
to a STSG if it was found to be practical. 

Sparkin' and Drowning in Memphis ( 8" of rain in last 36 hrs), 
David Rieben