View Single Post
  #13   Report Post  
Old February 1st 05, 08:31 PM
Reg Edwards
 
Posts: n/a
Default

Beyond 3 or 4 turns on a single-layer coil, the coil's resonant
self-capacitance is not very much related to capacitance between adjacent
turns.

This is because the individual between-turn capacitances are all in series
with each other and the resultant rapidly decreaes.

For a 10 turn coil the end-to-end capacitance due to adjacent turns is only
1/10th of the individual turn-to-turn capacitance.

Coil self-capacitance soon becomes a linear function only of coil diameter
and length of the coil former.

It's rather complicated but the resulting self capacitance is much smaller
and the resonant frequency is higher than what you think it might be just by
considering the individual turn-to-turn capacitances.
----
Reg, G4FGQ