[R-390] BNC to MB adapter?

[Dan Merz]

Hi,  I need an adapter to take one end of  a  BNC jumper cable to type
MB,( the small bayonet connector in a 390a).  I believe this adapter is
an Amphenol 47200 connector,  like the i.f. output connector on the back
of a 390a.  I am going from the BNC connectors on a 390 i.f. chassis
(male bayonet/female pin) to the corresponding two MB (female
bayonet/female pin) cables on a 390a.   I need two of these adapters.
Does anyone have a couple of these to spare, know where I could find
them,   or know of another type of connector that will do the job
without altering the connectors on the 390a?  thanks,  Dan.