[AMPS] Chokes

[Tom Rauch]

Someone said:

> The highest L  choke that has no resonances below 30MHz is c. 65uH.  
>

That isn't true. 

The resonant frequency varies greatly with capacitance, and how 
that capacitance is distributed. Even what the choke is around 
changes the resonant frequency.

Physically small chokes have much higher series resonant 
frequencies than larger chokes, even when the inductance is the 
same.

Stray capacitance at the middle of the choke is the problem at the 
first resonant frequency, so removing turns there and making an air 
gap will shift the first series resonant frequency higher.


73, Tom W8JI
w8ji@contesting.com

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