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

[Jordan Arndt]

The crystal oven is octal based, and can sometimes be hard to remove, as are 
many of the tubes..!

If you're not seeing the 17.000xxx signal, that would explain why the bottom 
8 bands are dead, as they rely on that signal for conversion and mixing.

I'd just continue to rock and pull on the oven and it will eventually break 
free so you can extract the oven plug-in.

Worst case, you might end up pulling the outer cover off the base due to 
your efforts, which also can happen. If that happens, it will expose the 
"cover" over the two xtals installed in the oven chamber. That cover can be 
removed


I hope this helps...

73..Jordan VE6ZT


----- Original Message ----- 
From: "brianpepperdine brianpepperdine" <brianpepperdine at sympatico.ca>
To: "r-390" <r-390 at mailman.qth.net>
Sent: Thursday, November 11, 2021 12:38 PM
Subject: [R-390] no signals below 8 mhz,crystal oven removal for xtal 
testing etc


> 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
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