[TowerTalk] Ferrite core spacing?

[Roger (K8RI) on TT]

On 7/28/2014 11:06 PM, Jim Brown wrote:
> On 7/28/2014 7:38 PM, Jim Brown wrote:
>> On 7/28/2014 6:04 PM, Roger (K8RI) on TT wrote:
>>> Would it make any difference if the cores in a stack of 6, 
>>
>> I would say no.

Thanks Jim.

The capacitance makes sense...although the core area is the same, it 
would probably appear as moving the plates apart on one side of an air 
capacitor.
I would think then that an extra turn or two would compensate?

I'll be using RG-400, or other  small,  relatively high power Teflon 
dielectric coax with plenty of room for additional turns.
The small coax makes for a neater and easier to wind choke.

HOWEVER: Using a guide for the early turns and wire pulling soap for the 
last two I can get 6 and possibly 7 turns of LMR-400 or Davis BuryFlex.  
Turn #7 may take some perseverance. and care to keep all passes through 
the cores, straight!

These have 6 turns http://www.rogerhalstead.com/ham_files/AntennaFeed1.htm


>
> I'm going to reverse myself on this, Roger. The inductance and coupled 
> resistance won't change, but there will be less stray capacitance with 
> the cores not touching, and capacitance is an important component of 
> pulling the resonance down to where we want it.
>
> 73, Jim K9YC

73

Roger (K8RI)

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