RE: measuring the resonant frequency of the secondary

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

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >You have to use a signal generator with very low output impedance to
 >see the peaks cleary.

To check the tuning of a complete TC (primary and secondary together) I like
to use a ferrite transformer to couple the output of the sig gen to the
primary. I connect the sig gen to a 30 turn winding on a ferrite ring, and
drive the TC tank circuit from a single turn secondary (an alligator clip
lead passed once through the ferrite ring, and hooked across the TC spark
gap)

This works great with an old HP 200 style tube oscillator- these have a
generous output of ~40V into 600 ohms. It actually excites the TC enough
that I can pick up the secondary output from a scope probe held in mid-air
about 2ft away, and see the resonant frequencies that way. I can also see
the oscillator's output voltage being loaded down at the resonances.

To test the secondary alone, you can base drive it directly from the
oscillator (connect one lug of the oscillator output to the secondary base,
and the other to a groundplane, or the AC line ground.)

Steve C.