[time-nuts] Morion MV89A Repair

John Miles jmiles at pop.net
Sun Feb 26 00:02:27 UTC 2012

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-
> bounces at febo.com] On Behalf Of Bob Camp
> Sent: Saturday, February 25, 2012 2:55 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Morion MV89A Repair
> Hi
> The spectrum you show in the middle is the correct one. It shows the 10
> output and the sub-harmonics related to the 5 MHz crystal oscillator. The
> other two are a bit broken. One appears to have a stage oscillating. The
> other is more interesting. It has a stage oscillating that is injection
locked to
> the 5 MHz crystal oscillator. I suspect more than one capacitor went bad
> these OCXO's. Somebody may have sold Morion a bad reel of bypass caps.
> Bob

Interesting.  The MV89As are very stable, but they have a lot of AM noise
and they don't meet their PN specs (about -150 dBc/Hz at 10 kHz rather than
-155).  I've tested a few and they all look the same in that respect.
Sounds like replacing all of the SMT caps may be a good move.

-- john

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