Hello Chris,

I use the term “isolation” to emphasise the fact that it does provide galvanic 
isolation, which an auto-transformer does not. 

The transformer here is a ferrite ring type N90AB from Maplin, with a 5 turn 
primary winding and a 10 turn secondary. The transmitter is a 30 W class E 
design based on the spreadsheet by G3NYK. In this configuration, with the 
antenna system presenting 50 ohms, the amplifier sees the desired load of about 
12 ohms.

73 John F5VLF

> On 16 Oct 2015, at 00:44, Chris Wilson <[email protected]> wrote:
> 
> … Another poster, John Rabson, talked of isolating mains
> ground and RF ground. As I have had occasional RCD trips at the house
> distribution panel when TX'ing at high power with this setup, I am
> wondering about this. He spoke of an isolation transformer, but I am
> not sure just what he meant by that. 

[email protected]

Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and ROBSONNE