Are you thinking of a Bias-T? MFJ sells them with some of their tuners. -73- Frank KG9H [email protected]
> On Dec 3, 2021, at 5:53 PM, Andrew Ikin <[email protected]> wrote: > > 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 > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
