[time-nuts] Convert Stanford Research SR620 time-interval counter to SR625 ???

Magnus Danielson magnus at rubidium.dyndns.org
Thu Nov 27 18:02:29 EST 2014


On 11/27/2014 11:37 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> On 27 November 2014 at 22:15, Brooke Clarke <brooke at pacific.net> wrote:
>> Hi David:
> Hi Brooke
>> If you look just to the right of the SR620 you will see a separate box that
>> contains the PRS10.
> Ah, I missed that!!!
> I was thinking it fitted inside the SR620, but obviously not.

Having both, I'd say that it would be a difficult task to do, without 
even attempting to measure.

>> The PRS10 can work as either a Rb GPSDO or as a time stamping device.  For
>> the SR620 any GPSDO would make a good external reference.
> It would have been nice to have a better reference inside, as
> sometimes I move equipment around, and don't always want to take more
> than necessary, so having a better reference inside would have been a
> nice thing, but I see it is not what I thought.
> This unit I purchased has the option 01, the ovenized VCXO, but of
> course that is not going to have the long-term stability of a Rb
> source.

This is their SC10 SC-cut OCXO, which is pretty good actually.

If you do the calibration every now and then you should be fine.

One of the uses for rubidiums was that the counter wasn't as sensitive 
to being turned around, which proved to be a problem in field 
calibrations of base-stations (up on ladders and other crazyness).

The only real benefit of the 625 is a neat combo.


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