# Re: Newbie Question

```Original poster: Jared E Dwarshuis <jdwarshui@xxxxxxxxx>

Hi Jay, sorry about the delay in responding, I got caught up in
building a ballast for a pole pig......

A quarter wave has a current node by the primary and a voltage node at
the very top. A half wave has a current node in the center of the coil
with voltage nodes of opposite polarity at each end.

An easy way to build a half wave is to wrap 10 lb of 22 gauge on a 10
inch cardboard concrete form.

The frequency to drive the tank circuit is simply the speed of light
divided by twice the wire length used. (it should be very close to
96,000hz )

To calculate the total top end capacitance measure from the center of
the coil to the end and use 45.07 pf per meter height (roughly
30.4pf)  and subtract  Medhurst self capacitance from the region

This gives us a total top end capacitance of 16.4 pf. Then we know
that each capacitor must total 8.2pf. ( a six inch sphere for each
side will work nicely, and you can use 3/8 inch copper tube for
routing the spheres)

A 27 inch to 30 inch diameter solenoid primary will work well ( I
prefer 30 inch )

An NST system with a forced air gap is the easiest and cheapest rout
for a tank circuit. But solid state would be the first choice if
portability was the main concern.

Sincerely: Jared Dwarshuis
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