Re: Revised version of the HF Antenna isolator
Chris,toggle quoted messageShow quoted text
I have been following the discussions on the Antenna Isolator, following on from your article in RadCom on Loop Counterpoises, with extreme interest.
I am concerned at your (strong) recommendation of a Ferroxcube core with a 4A11 mix for the transformer. The part is identified in both the text and in the schematic, so I am sure it isn't a mis-print.
It is hard to source in the UK, anyway, but it seems to have a very low u' for LF work. Ferroxcube's data sheet suggests it has a u' of only 850. They rate the material for transformers from 10 - 1000MHz. For LF bands, I was expecting something around 3000 for u'. Can you put me right, here?
From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Chris Moulding
Sent: 25 September 2020 19:57
Subject: [CrossCountryWireless] Revised version of the HF Antenna isolator
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: