[time-nuts] 10811 performance

[Bob kb8tq]

Hi

To that I would add - how long was it on power when measured? Does it run on power
24/7 at the club or is it power down 99% of the time? 10811’s (at least as much as other
OCXO’s) “like” to be power on all the time. However using it one way and calibrating it
another way may not be the best approach.

All this “fun” is one of the reasons for setting up a “lab standard” and piping it to all the 
gear rather than calibrating each item individually. With the Chinese packaged GPSDO’s
coming in at < $100 delivered it is not a major investment. That kind of thing may or may
not make any sense at all in this case. 

Bob

> On Dec 27, 2019, at 8:02 AM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> 
> Hi Robert,
> 
> If your 10811 10 MHz oscillator is off by 0.08 Hz after 20 years it's equivalent to an average frequency drift rate of only 0.08/1e7/20/365, or 1e-12/day. If so, you have an absolutely superb 10811; one that's 500x better than spec. Congrats! Don't power it off, don't touch it, don't move it, don't tilt it, don't sell it.
> 
> Still, there are a lot of assumptions here:
> 
> - Do you know how closely was it calibrated 20 years ago?
> - Did anyone measure it once a month or even once a year since then?
> - Do you have reason to believe the frequency drift rate is constant or predictable?
> - What's the environment been like (temperature, humidity, pressure)?
> - How much do you trust your cheap China GPSDO?
> - What does your 53131A counter say over gate times of 10 s or 100 s, and over an entire day or week?
> - Was this a one-time lucky measurement or is your 10811 really this good day after day after day.
> 
> Lots of questions. What I mean is that you may have one of the best 10811 ever seen, or something's funny with the above assumptions. The nice thing about a precise time & frequency hobby is that, without too much effort, you can figure this out.
> 
> Still, 0.08 Hz out of 10 MHz is 1e-8, or 0.01 ppm, or 10 ppb, so depending on the accuracy that you need for the amateur radio club, it may be plenty good enough as-is.
> 
> /tvb
> 
> 
> 
> On 12/26/2019 8:51 PM, Robert DiRosario wrote:
>> I am trying to calibrate some equipment at the amateur radio club at work, and my stuff.  We have an HP 5340A with a 10811 inside. It must have been upgraded at some point in the past, the display uses Nixie tubes.  I calibrated it c2000 using a HP Cs standard. That lab and it's equipment are gone.  :-(
>> 
>> From ebay / China I got a simple GPSDO that uses a Trimble 57963 inside.  I use the output of the 10811 in the 5340A to drive an HP 53131A.  I then measured the 10 MHz output of the GPSDO using the HP 53131A and got 10,000,000.08 Hz.
>> 
>> Assuming the GPSDO is correct, is 0.08 Hz drift over 20 years a reasonable amount of drift for an 10811?
>> 
>> I have an HP Z3801A, once I get a power supply for it I can check the other GPSDO.
>> 
>> Thanks
>> 
>> Robert
>> KA3ZYX
>> 
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> 
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