Topband: Ground loop isolator that passes DC

[Andrew Ikin]

Chuck Hutton,

Wrote on Dec. 3.

<Many years ago I saw some ground loop isolators that pass DC.
That is exactly what I need so that power can be sent over coax feeds to
preamp at the antenna.
I cant find anything on eBay that mentions passing DC in an isolator. None
of the isolators I have will pass DC.
Does anyone know an isolator that passes DC? I would like to avoid building
one.>

I guess what Chuck means, is a Ground loop due to the antenna end of the 
coax. screen being connected to Earth thus causing the feeder shield to 
become a loop antenna with the ground RF return path to Rx. Hence, resulting 
in excess noise pick-up.
Normally common mode choke will be of benefit. But I would guess that Chuck 
has already tried this.

One option could be fit a 1:1 isolation transformer at the Rx input or into 
the Bias T. Then use a floating power supply to the drive antenna pre-amp.. 
A bias T that already has a common mode choke on the DC input would help 
too.
The Antenna Interfaces manufactures by Wellbrook have this choke feature.

73

Andrew  Ikin  G8LUG