Jeff wrote in :

As a matter of interest why are you looking at 75ohm cable, when most
people and equipment use 50ohm.


Good point, though last I read of that, it was the other way round.
(Depends on context). At least, most times I had a device that needed RF
coax, it specified 75 ohms if it didn't come with cables made for it. In my
current case, it's not clearly known what other impedances are involved in
an SWL setup, but they're almost certainly higher than 75 ohms, so going for
a 50 ohm coax seems unwise.