Re: [IRCA] Cable connectors

[Rick Kunath <k9ao@xxxxxxxxxxx>]

Another interesting idea...

n Monday, September 06, 2010 06:12:46 pm Craig Healy wrote:
> The goal is to reduce the signal ingress on an antenna cable to the lowest
> possible level.  What if the receive end was run through a transformer to
> open the ground connection.  Then, a single wire was run parallel right
> next to the coax for the entire length.  Then coupled out of phase with
> the shield on the coax itself?  I have to wonder if that could be tweaked
> to drop the ingress signals by canceling them out?  A 180 degree
> transformer keeps that phase over a wide frequency range so it wouldn't be
> a
> frequency-specific null.

Had you thought about using a transformer at the receive end that had a 
symmetrical center-tapped primary winding (antenna side), with the center-tap 
connected to your ground system, and then an isolated secondary connected to 
the receiver?

That would shunt the common-mode currents to ground, rather than looking like 
the open circuit that the choke on the shield would. You could also do an 
impedance transformation from the 100 ohms of CAT cable to your receiver's 50 
ohm input.

Possibly one of each, high impedance at the ends of the cable run and then 
after that the shunt transformer, then out via the other winding.

Kinda of rambling here, but that way you would impede the flow of common-mode 
currents and then shunt to ground any that remained.

Seems to me that a plan like that would work best on balanced line. 

Anyway, just a thought.

Rick Kunath

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