[R-390] MB Connectors (was) Info wanted

[Chris Farley]

OK gang here's the lowdown-

These are conclusively, simply considered "2 stud Miniature Bayonet" connectors-  AKA "MB".  


The original R-390A connectors were Automatic Connector type 

Straight- RF-0701-23 (Amphenol 45425)
Right angle- RF-0702-23 (Amphenol 45875)

There are other Amphenol numbers that cross reference.  Later on, connectors were used with a larger, plastic compression nut system instead of silver plated brass.  I have not yet found numbers for these.  

The small adapter cables John offered up appear to be for a larger OD coax-  Although still quite useful, keep that in mind before hoarding them up.  The correct connectors are rare because of the compression nut hole size, meant to work with the 0.085" OD coax.  Which incidentally, was NOT originally a 50 ohm cable-  It was originally Suprrenant type 70-390-12 which is:
70 ohm 

0.085" OD

Teflon insulation
Nylon sheath

20pf/ft 

#29 solid conductor (changed to stranded in 1966)

Supposedly this was changed to a 50 ohm cable for the Fowler contract radios, but I have not yet with my own eyes seen paperwork, nor have I access to one of the radios to physically look.  

You do NOT want to know what surplus houses want for these connectors-  Believe me, I've been down that road.