Revised version of the HF Antenna isolator

Chris Moulding

Following the publication of my recent article on loop counterpoises for low noise vertical antennas in the RSGB RadCom magazine, I've had a lot of feedback from RSGB members trying the design.

One question that came up a few times was could it be used with the non-resonant HF verticals such as the popular 43 foot vertical?

To work with those antennas the HF Antenna Isolator would need a 200 ohm output so I've re-designed it to have both 50 and 200 ohm outputs along with the 1 M ohm resistor and 20 kA gas discharge tube to provide protection from static electricity on the antenna.

It's now available.

The web page is:



Join to automatically receive all group messages.