Well after a real struggle with the semi-rigid cable I managed to finally
get the preamp into some sort of a box. The unit is powered up the coax,
the preamp has been slightly modified to extract the DC supply from the coax.
This also feeds the 18 GHz 12v relay. I managed to find a small quantity
of 12v relays rather than the usual 24v ones.
I must admit I don't really want to put the preamp outside any more instead
I am going to place it where the coax enters the building. That will still cut
down on the distance between the antenna and the preamp.
When no supply is applied to the coax the transmitter is switched straight
through to the antenna in a fail safe manner.