[TowerTalk] choking multiple wires..

[Jim Brown]

Hi Jim,

See comments inline.

On 7/30/2020 1:01 PM, jimlux wrote:
> In an effort to keep the control and power wires to the remote tuner 
> from being "part of the antenna", I'm planning on choking it with a 
> cookbook design from Jim's book.
> 
> The question is, I would think I can take all the cables and run them 
> together through the cores as a "bundle" for this kind of thing. After 
> all, they're capacitively and inductively coupled by being in close 
> proximity, so from an "antenna" standpoint, it's one wire.

Yes. BUT -- an important design variable here is the parallel parasitic 
capacitance in the equivalent circuit of the choke, which combines with 
the inductance and resistance coupled from the core to "tune" the choke 
to the frequency(ies) where suppression is needed. My "cookbook" 
recommendations are based on measuring several specific cable types and 
a specific winding style. Deviate too far from that and you're on your 
own! :)

> Also, better to have big chokes at carefully chosen locations (Where?) 
> or just put small choke at some interval of something like 5-10 ft. 
> Overall series impedance would be the same, but it's broken up.

The optimum locations for chokes are as close as possible to the noise 
sources and to victim electronics.

As noted in my latest cookbook, measurements showed that it is critical 
that windings progress in order thorough cores without "crossover" 
windings.

73, Jim K9YC