[time-nuts] Selling Time and Frequency Equipment Or "just saying"

Tom Van Baak tvb at LeapSecond.com
Mon Feb 26 06:37:05 EST 2018


Corby,

Thanks for your informative posting. I concur. Let me add a visual that echoes your comments. It's the same plot that I attached in the note about Ralph's lab. For those of you who can't view email attachments see [1].

The plot is ADEV of 4 typical lab frequency sources:

- A 5071A in Ralph's lab, on loan from NIST.
- A 5065A Ralph owns, which has some 120 Hz noise, but excellent stability beyond tau 1 s.
- The 10 MHz ref out of a Agilent/Keysight 53230A counter (XO or TCXO, not sure).
- The 10 MHz ref out of a SRS SG348 signal generator (OCXO option).

Note the difference between the 5065A and the 5071A in the plot. You can see why for many experiments a 5065A is preferred. I mean, over a wide range of tau it's 4x better. OTOH, if you want to make short-term measurements against a cesium standard, by all means turn off the Cs beam and let it free-run. Both the 5061A and 5071A make this easy.

/tvb

[1] http://leapsecond.com/tmp/2018b-Ralph-4-adev.png


----- Original Message ----- 
From: <cdelect at juno.com>
To: <time-nuts at febo.com>
Sent: Saturday, February 24, 2018 2:14 PM
Subject: [time-nuts] Selling Time and Frequency Equipment Or "just saying"


> First, full disclosure, I have no vested or financial interest in the
> 5065A he is selling.
> 
> Now the 2816A prefix is the last series built so the most modern.
> The last one I remember on eBay went for OVER $4000.00
> 
> Comparing a 5065A to a Cesium (except maybe a working 5071A for the same
> price)\is worse than Apples and Oranges.
> 
> Ask Bert who got rid of his 5065A years ago because he had a Cesium, he
> regrets that now and just got a new one!
> 
> A 5065A buyer is looking for the best short term stability he can find
> (nominal 1.5X10-13th at 100 Sec)
> Keeping on frequency is easy via GPS comparisons.
> 
> A Cesium buyer want NIST traceable accuracy "out of the box" and never
> (practically) having to adjust the frequency. The Cesium will be worse
> when  compared to the 5065A at shorter Tau even if it has a high
> performance tube.
> 
> Another thing to consider when buying a Cesium is what is the condition
> of the tube. The tube will die, just don't know when. (probably at the
> most inconvenient time!), and lets not ask what a replacement tube costs!
> 
> There is no perceptible wear mechanisms in play for the 5065A (I have
> seen exactly one failed lamp in many years of working on them) Many of
> the first 1968 series built will still perform to specs today.
> 
> So,
> 
> Just saying!
> 
> Cheers,
> 
> Corby

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