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
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