[R-390] no signals below 8 mhz, crystal oven removal for xtal testing etc

[brianpepperdine brianpepperdine]

It was suggested that I bring my question to this List, so I have joined up...
here goes...

My R-390A lost reception below 8 mhz. This is the triple-conversion operation of
the receiver, thus I have turned my attention to the first mixer area etc.,
which includes the 17 mhz injection via the crystal oven.

I swapped out the 6C4 and another 6C4 in the mixer chain (interchanged) and it
runs still OK above 8 mhz in Double Conversion mode, so the 6C4 is fine I think.
V207 (5654) tube is bit hard to get at... so the other issue to be looked at is
the 17 mhz crystal in the HR202 crystal oven. If I take out the oven in theory I
can swap in (temporary) a 17 mhz xtal from elsewhere in the receiver xtal bank.

Based on a suggestion, I do not see 17 mhz at the P221 jack as per my frequency
counter.


However, the xtal oven seems resistant to being pulled out... the Y2K 390A
manual talks about a spring retainer on top of HR202 (I have none). It seems to
me that HR202 is sort of in a tube socket kind of thing (as per diagram) but
with any gentle tube removing kind of movement (gentle rocking and pulling) it
does not seem to budge. I don't want to really 'wrench' on it. It IS in a socket
arrangement, right? Not hard wired....?

In any case, having the xtal swapped in would help diagnosis or fix.. but even
so
its lack of presence would also help me in getting my fingers into the tight
space to remove V207  5654 tube out to test it (it does glow, but what does that
really
mean in the Grand scheme sometimes).

Anyhow any opinions on the xtal oven removal would be appreciated...
or ideas on loss below 8 mhz reception.
I hope its not a transformer (one other possibility) because then we are
getting way beyond my level of competence ( and obvious lack of spare parts).

Tnx
Brian VE3HI