Terry Casey wrote:

I saw a anumber of these so there is no doubt in my mind
whatsoever that they were F connectors!

Back in the 80's I used thinwire ethernet, arcnet (plus various twisted
pair rather than coax cabling) none of them had F connectors all BNC,
the PC cards that *did* have screw on rather than bayonet were IBM
AS/400 and 5250 twinax connectors ...