Question on calculating resonance

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Original poster: "Angelini, Frank J" <FrankJAngelini@xxxxxxxxx>


I saw this diagram in an old magazine describing a horizontally 
oriented tesla coil.  The secondary was approx 6-inches in dia and 
about 24-inches long.  The primary was 8-inches in dia and maybe 10 
turns of edge-wound copper strip.  The primary was mounted in the 
center of the secondary and both were horizontally oriented. The 
primary was center-tapped and connected to a straight gap as 
shown.  Not sure of the sec. winding length or cap values.  T1 was 9 
kV @ 500 VA.

Question:  how would you calculate cap values for resonance?  I 
thought, perhaps, that this is in effect, two 1/4-wave primaries and 
a 1/2-wave secondary.