[time-nuts] What sort of oscillator is this?

Bob Raker bob.raker at gmail.com
Mon Sep 29 12:28:11 EDT 2014

It is a low end OCXO - uses AT cut crystal.  15V @ 300 mA.  Warm-up time is
6 minutes max for .1 ppm.  Other specs as indicated in previous emails.


On Sun, Sep 28, 2014 at 7:26 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> There were two responses to Dave's question (TCXO and OCXO) and perhaps
> neither is correct. I don't have a 8720D VNA myself and Dave wisely doesn't
> want to spoil his calibration seals by opening up his instrument to take a
> look inside. So here's my guess based on the clues.
> "Agilent 8719D, 8720D, and 8722D Network Analyzers Data Sheet"
> http://literature.cdn.keysight.com/litweb/pdf/5964-9133E.pdf
> Base spec:
>     Stability 0 °C to 55 °C ±7.5 ppm C
>     Per year (aging) ±3 ppm C
> Option 1D5:
>     Stability 0 °C to 55 °C ±0.05 ppm C
>     Per year (aging) ±0.5 ppm C
> "Installation Note 8719D, 8720D, and 8722D Network Analyzer
> Option 1D5 High Stability Frequency Reference Upgrade Kit"
> http://literature.cdn.keysight.com/litweb/pdf/08720-90318.pdf
> High-stability frequency reference output (Option 1D5)
> Frequency: 10.0000 MHz
> Frequency stability (0 °C to 55 °C): ±0.05 ppm
> Daily aging rate (after 30 days): <3 x 10–9/day
> Yearly aging rate: 0.5 ppm/year
> Output: 0 dBm minimum
> Nominal output impedance: 50 ohms
> To me, these specs are a bit better than all XO and most TCXO I've seen
> used in test equipment. But the specs are a bit worse than most OCXO I've
> run across. So which is it, TCXO or OCXO? The next clue is the attached
> photo found at:
> "Agilent 08753-60158 Opt. 1D5 for 8753D/E/ES"
> http://www.ebay.com/itm/151256172424
> So we're looking for the specs for a Corning oscillator, P/N MC599X4. I
> didn't find much on the web (one link called it a "controlled oscillator").
> Does anyone have information on this? It looks too large for a XO or TCXO.
> MC might be McCoy. Or, if MC indicates MCXO (Microcomputer Compensated
> crystal Oscillator) then that would nicely explain the shape/size and why
> the specs are in between a really good TCXO and a not so good OCXO.
> Some photos of the inside of a MCXO (not necessarily the one in question)
> here:
> http://design.ecs.psu.edu/2.0/Design/design_images/MCXO1.jpg
> http://design.ecs.psu.edu/2.0/Design/projects2.html (scroll down to MCXO)
> /tvb
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