[TowerTalk] 12V through coax to switch antennas remotely

[Steve Bookout]

Tony,

My apologies.  I re-read your email and see your dealing with receive 
only antennas.

You may ignore my post, as current/voltage will not be an issue.

I had always heard the reactance should be 10 - 12 times the impedance 
your dealing with, so at least 600 ohms reactance for the choke, which 
is about 50 uh at 1.8 MHz.  Easy to go more and doesn't hurt.  I think I 
use 75 to 100 uh.  I don't recall exactly.

The cap can be almost any amount.  A .01 uf will give your about 5 ohms 
of capacitive reactance at 160.

Steve, NR4M

On 4/3/2018 9:32 AM, N2TK, Tony wrote:
> Have a question about the values of the choke to keep RF from the relay and
> the caps for coupling of the signal. In different products I see quite a bit
> of different values of both components.
>
> For the coupling caps I see values from .01-.2uf. It would seem increasing
> the value of the cap reduces the Xc. And for the choke I see values of
> 100uh-2.5mh. And it seems increasing the value of the choke also increases
> Xl.
>
>   
>
> My application is for 160M and 80M only with receive antennas.
>
>   
>
> My question - does it really make a difference over the values listed above?
> Do all the values offer enough Xc or Xl to not cause any problems?  Is there
> really a recommended "good" value for the caps and coils? Even 100uh offers
> 1K ohms at 1.8MHZ and .1uf is .8 ohms.
>
>   
>
> Still learning.
>
> Tnx
>
> N2TK, Tony
>
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