Dave, do you have access to a good counter? If so, you could profile the
warm-up characteristic of the reference from a cold start. Then you would
know if an oven is involved.
Tom
----- Original Message -----
From: "Tom Van Baak" <t...@leapsecond.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Sunday, September 28, 2014 7:26 PM
Subject: Re: [time-nuts] What sort of oscillator is this?
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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