[R-390] Question about R-390 Calibration Osc

[Bob Camp]

Hi

For the multi-vibrator to work correctly, it needs to be a bit *low*  
in frequency. It sounds like yours is simply running a bit to high.

Bob

On Jun 5, 2007, at 5:28 PM, Grant Youngman wrote:

> Simple question.  Is it normal for the multivibrator in the cal  
> oscillator
> to require the radio to warm up well before synchronizing with the  
> 1 Mhz
> oscillator?
>
> Calibrator operation has been iffy at best, so since I had the  
> radio out of
> the case to replace a bad 6082, I decided to tackle the calibration
> oscillator issue.  It's basically hard to keep the 100Kc multi  
> synced to the
> master oscillator.  If I set the sync adjustment when the radio is  
> cold to
> sort of warm, it loses sync as it gets hot.  If I wait until it's  
> hot to
> adjust it, it won't sync until the cold radio has been on for 15-20  
> minutes.
> And then it will occasionally lose sync for a while, then resync --  
> always
> out of sync seemingly when I want to change bands and reset the  
> dial :-)
>
> The 1 Mhz oscillator appears to be ok.  New tubes (which seemed to  
> help
> somewhat at first, but ultimately not so much)
>
> Is this normal?  Or is it reasonable that something in there that has
> possibly degenerated and become temperature sensitive (such as  
> C-909 or
> C908)?
>
> Any suggestions on what to poke at first? -- it's a tight spot to  
> work in
> there.
>
> Grant/NQ5T
>
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