[R-390] Troubleshooting the R-390A Rf Module

[DW Holtman]

Hello,

I have an unusual problem. I'm in the process of trouble-shooting an RF 
Module on an R-390A.  The problem is the 17 MHZ xtal oscillator V207 does 
not want to turn on. For some reason, if I put a tube extender in the socket 
then put in the tube to take some measurements, it starts working. Does it 
want more/less inductance or capacitance?

The tube has been swapped.

The resistance and voltage checks are within specs.

A good visual shows nothing.

When it is oscillating (with the tube extender in place) the output 
transformer, T207 adjusts and seems to be working.

Has anyone run into a similar problem with this circuit or another xtal 
oscillator?

Thank you,

DW Holtman