Strange sweep results

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Original poster: "Sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sundog-at-timeship-dot-net>

Hi All,

   I have a strange problem.  I got my new signal generator (B&K 4001), and 
it works like a champ.  My scope is giving me some fits (must be jealous), 
but everything is working now.

    I immediately swept one of my small 2.5" coils.  And got the expected 
Fres of around 833khz.  Sweet.  But, upon winding the generator up a bit 
more, I ended up with another spike at 2.5mhz.

   I'm a bit confused.  At harmonics I get a nice double-sine waveform, 
with a big and small hump.  I've seen it a million times sweeping coils, 
but never have I seen a smooth sine wave out of the secondary for anywhere 
except resonance.  It's strange allright.  I can't make heads or tails of 
it.  I know that Fres is 833khz, that's about what it works out to when I 
do it by hand, and that's what the sweep tells me.
   Normally, on a harmonic, the amplitude of the input sine is far less 
than it is at resonance, but this one is just as strong as the real 
Fres.    I'm confused now.  Should I set my tank frequency to 833khz or 
2.5mhz?   Or should I try both and see which gives better performance?

Curious,

  Shad G3-1203