Fwd: Tap tunable secondary

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

Original poster: "Troy Peterson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tpeterso-at-home-dot-com>


Hiya Terry,

What about a sectioned coil... Like a bunch of small coil segments that 
snap together using some simple, yet ingenious locking method that I'm sure 
you could come up with. I've seen telescopic coils before, but this does 
not change the winding length, if the secondary coil actually consisted of 
a series of small secondaries that you snapped together you would have 
quite a bit of control over it's frequency without any of the nasty 
problems associated with taps.

just a though...

Regards,
Troy Peterson <www.video-vertigo-dot-com>
VE7SOK


>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