[RFI] 2.4" OD #31 toroids

[Pete Smith N4ZR]

Jim,I had assumed that I could achieve an impedance of over 5000 ohms 
with a single #31 core and 14 turns of RG-59, based on Figure 18A of 
your ferrite tutorial.  I see that your later graphs using RG-8X assume 
a 5-core stack, but achieve higher impedance with fewer turns.  For a 
single-band application, I'd think a single core per choke in that 
center-ground arrangement would be good enough, wouldn't you?

73, Pete N4ZR
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On 1/31/2012 11:44 AM, Jim Brown wrote:
> On 1/31/2012 3:10 AM, Pete Smith N4ZR wrote:
>> Jim's original cookbook used multiple cores in each.
> There are two good reasons for using multiple cores. One is power
> handling. The other is to get enough L and C to move the resonance low
> enough to cover the frequency range of interest.  L increases as the
> square of the number of turns, C increases as the number of turns (not
> squared). Both lower the resonance. The impedance at resonance also
> increases with the number of turns -- not linear, not squared, because
> resonance is moving down. At any given frequency, the resistance coupled
> from the core DOES increase as the square of the number of turns.
>
> 73, Jim K9YC
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