Re: Scoping of Secondaries

Glenn Baddeley writes...

> The base of the secondary is earthed via a low value
> resistor, and the CRO is strung across the resistor.
> The resistor value is a compromise between getting
> enough reading on the CRO and it not affecting the
> resonance very much.  100 Ohms or less seems about right.

My finding is that when it comes to high Q coils, 100 Ohms series R
is a VERY significant value compared to the AC resistance of the coil.
    Earlier this year I measured the effects of various earth leads
of different types on the Q of a secondary coil. Even with a primary
secondary coupling reduced to less than 0.01, the nominal Q of the 
coil was lowered by around 20%. I was still able to detect nominal
differences between the best wires and very large differences between
the best and worst.