Re: Off-axis primary inductance
In a message dated 12/8/98 3:33:37 AM Mountain Standard Time, tesla-at-pupman-dot-com
> Inductance depends on the number of turns. I have a variometer here
> which has an inductance range from 3500 microhenries to 8000
> microhenries. Have made several with somewhat lower inductance. As for
> the insulation, the thing is just a couple of coils, so isn't any harder
> to insulate than the TC primary or secondary.
What I had in mind is a variable inductor that is adjustable from 0 to
about 10 uH. This would allow fine tuning equivalent to about one turn of the
primary. I decided that this would be too much trouble to build at the
moment. I made a tuning coil by winding some 5/16 copper tubing(with 1/4 inch
spacing) around a 3 inch cardboard tube. I measured 10 uH on the 15th turn,
so I believe this will do for me.
I just plan to tap this tuning coil as one would normally do with the
primary coil. The one advantage to this is that I won't have to make
connections all around the primary to hone in on the sweet spot. Once I get
it in tune, then I can have a good estimate of where to tap the primary and
remove the tuning coil from the circuit.