[time-nuts] 10811 performance

[Magnus Danielson]

Hi,

Do you aim to ensure that your 5340A is "calibrated"/adjusted as you
take it to the club?

If so, using the GPSDO and 53131A together is a good idea. If you can
setup so that you can log the 53131A using GPIB or serial port into
TimeLab, I suggest you shift from using the 53131A in frequency mode and
use it in TI mode, trigger the measurement with the GPSDO PPS into the
Channel 1 (Start) and measure the time-base output on the 5340A on
Channel 2 (Stop). Be careful to turn off the auto-trigger feature on the
53131A and set your own trigger point at say 1 V for the PPS. The 53131A
is impatient and the PPS is a too slow rate for it to handle the signal
right. Then you can fine-tune the frequency adjustment there and also
see how it shifts around which is very educational.

This setup would also be suitable to compare the GPSDOs with.

As you measure frequency, this can cause some systematic errors, but
those is avoided as you use the TI measurement, but direct frequency
measurement is good and direct enough to get you started.

For what seems to be your actual application, the above is overkill, but
very good exercise. You will find that after moving and turning on, the
oscillator will have a residual drift as you measure carefully, and for
most uses to calibrate your amateur radio stuff at the club, you will be
way overkill anyway, but this is time-nuts, and we enjoy doing overkill
because it is pretty easy to do and we learn by doing it over and over.

Cheers & 73 de
Magnus SA0MAD

On 2019-12-27 05:51, 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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