Re: Secondary resonant frequency: using a signal generator

> So I was wondering, how would one use such an item to find the 
> resonant frequency of his secondary?

You can hook it up like so:

                                       3  <--secondary
                                       3       coil
  -------------      1K resistor       |        ------------
  | Generator |--------/\/\/\----------|--------|  Scope   |
  |           |---------------------------------| or VTVM  |
  -------------                                 ------------

By hooking the signal generator up to the base of your secondary and measuring
the voltage, the first flat-line voltage dip you come to will be the resonant 
frequency.  Off resonance, your secondary will present a high impedence to the
signal and will give a high voltage reading on the scope/meter.  At resonance,
the coil will absorb the energy from the generator and the voltage reading will 
be low.

I used an old old old, cheap signal generator to tune my first coils, and 
even with the non-linearities, I could still pick out the resonant frequency.
Obviously, a better generator will look nicer, but you should be able to use 
what you have without any trouble.  Although I seriously doubt if you would 
need to do this, but if you really want to get quantitative about it, you can sweep 
your generator through it's paces without the secondary coil attached and graph 
the voltage as a function of frequency to give you an idea of what you're dealing 
with.  Then when you get a null with the coil attached, you can check to see if 
it's real or just your generator.

Steven Roys (sroys-at-radiology.ab.umd.edu)