[R-390] Antenna Relay Connections ??

[Richard W. Solomon]

I am finally getting the R-390A I picked up onto the bench. It came
without the Antenna Relay Assembly and has 4 coax connectors waving
in the breeze.
Luck was with me and one of the leads had a Panel Mount BNC to ?? Adapter.
What type is that small BNC looking connector ? I need to get another
adapter.
There is a hole in the back labeled "Sync Xtal Osc", I expect one of
those orphan cables goes to it.
Is that an input or output ?? I didn't find it in my rather quick
look through the manual.

But first out comes the little vacuum cleaner and brushes to remove
all the dirt. At least it wasn't stored in a Chicken Coop !!

73, Dick, W1KSZ