Thanks to all for information, until I can get hold of some more quality coaxial relays to build a 4 way polarity control box, I shall build the simple RHCP/LHCP switching unit as shown in the ARRL Handbook, this will allow me to switch between the two modes as needed, although I would like to try and build a complete unit allowing four modes of polarity control, when some quality coaxial relays are found. regards Gus