[TowerTalk] Best coaxial to make Chokes

Jim Brown jim at audiosystemsgroup.com
Wed Nov 13 00:07:03 EST 2013

On 11/12/2013 8:20 PM, Roger (K8RI) on TT wrote:
> may be wrong, but I've always looked at the solenoid coil as if it 
> forms two resonances. The choke itself forms a parallel resonant 
> frequency with a rather high Q So it may work on one or two bands and 
> it also forms a second resonant frequency with the overall coax length 
> which can be worse than no choke at all. 

That's a good way of looking at it, but also an optimistic one.  The 
resonance of the solenoid coil (no ferrite core) has a rather high Q (so 
it's a narrow resonance) and is usually much higher than the band where 
it needs to work, in which case the resonance is of no value. It's also 
optimistic that only one resonance will form with the coax. :)

73, Jim K9YC

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