ok folks..
I'm getting a headache thinking about this so I'm passing it to you
lot for 'peer review' while I go to the pub ... I forsee pints of
luverly bitter.

http://www.qsl.net/g8nxd/diodesw.gif ( 8k )

describes a train of thought.. Am I having an abberation here or will
it work as I intend?.

ie. switch between the IF strip on RX and MOD source on TX and route
relevant signals IN/OUT of the filter and mixer in the correct way.

Obviously blocking C's are not shown

cheers Mike W