Thanks guys for the various replies.
I'm was almost sure these are 2.4mm connectors (and not 2.92) because the HP literature for the 70820A refers to needing APC-2.4mm adaptors, plus they don't look like they will mate with SMA connectors (I didn't want to "force" one in and wreck it, so I'm not totally sure!). I browsed all the 70820A literature I could find, but didn't spot a definitive statement of what the front panel connectors were (perhaps there are options, I don't know).
Perhaps as Dave Kirby suggests, I'll try making a low offer on a couple of adaptors to SMA, and see if I get anywhere.
Steve G4KNZ.
