Tap tunable secondary

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi All,

Many thanks for the great ideas.  I never thought of "adding" a small coil
wound in the "opposite" direction to reduce inductance.  That will be easy
:-)  I could spend a lot of time figuring out the perfect coil to use, but
it is faster just trying it to see ;-)

Today, I and all the other "mad scientists" here in Denver, spent all day
today moving Bill Lemeiux to his new home (and giant garage :-))).  Bill
has literally "many tons" of HV equipment so my muscles may not be working
tomorrow :-p But I'll try to wind a coil anyway ;-)

Also met up with Dave McKinnon (D&M's High Voltage) today for a real nice
chat between moving large heavy high voltage transformers... ;-)))  Must
rest now...

Cheers,

	Terry


>Hi All,
>
>I am having problems tuning my CW coil.  It is run off a variable frequency 
>900 watt, 325 to 375 kHz, industrial plasma power supply.  I can wind 
>matching transformers on big 3C8 cores to fix input impedances, but the 
>frequency is a problem.  It has a master oscillator frequency control so it 
>does not track with fancy feedback, PLLs or anything like that.  But I can 
>adjust the frequency by hand.
>
>The problem is the secondary frequency.  If I place different top loads on 
>it (like the power arc tonight) It tends to drop the optimal resonant 
>frequency too low and I can't get to the optimal frequency given the power 
>supply's range.
>
>So I was thinking of making a new secondary with tap points on it so it 
>could be taped at different frequencies.  About 5 inches on one end will 
>have a bunch of wire loops coming out.  I don't know if it would be best to 
>put these taps at the top or bottom of the coil.  I am worried about 
>autotransformer action and other problems with the unused windings.  
>
>Any thoughts on this are welcome.  I don't remember anything like this being 
>discussed before but maybe the long time tube coilers have run into this and 
>have some ideas.  I want to pump the full 900 watts forward (plus 250 
>reflected if needed) into a power arc to see if I can make the sparks Richie 
>got.
>
>Cheers,
>
>	Terry