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

Neil Schroeder gigneil at gmail.com
Wed Dec 3 12:08:32 EST 2014


Slightly deviated topic : I haven't really ever been able to talk to my
prs10 via serial and change or check my PLL status/settings.  Any tips
here??checked the internal jumpers and resistors.


On Thursday, November 27, 2014, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> > On Nov 27, 2014, at 8:05 PM, Don Latham <djl at montana.com <javascript:;>>
> wrote:
> >
> > I’ve just replaced the SR620 oxco option 01 with a Morion, by simply
> adding a 7812 to the 15 v heater feed. Locks well with either gpsdo or
> cesium external source. Don’t forget to turn on the external option and set
> the frequency for 5 or 10 MHz. It took about 5 days for the Morion to
> reasonably settle down.
> >  I agree about the Rb, has to be set with Gpsdo anyway, and I’ve already
> had 2 of them go South.
>
> I’ve had much better luck with Rb’s once I started heat sinking them
> properly. I pretty much ignored that issue early on and would regularly
> loose them. So far I have not lost one with a decent heat sink (and sub 40C
> baseplate).  Without heat sinking, some of them are up around 60-70C on the
> baseplate. Internal temps are even higher.
>
> Bob
>
> >
> > Prescalers from RFBay.
> >
> > Don
> >
> >> On Nov 27, 2014, at 4:25 PM, Brooke Clarke <brooke at pacific.net
> <javascript:;>> wrote:
> >>
> >> Hi David:
> >>
> >> For me the key benefit of the SR620 is the 16 digit display.  That
> implies a lot of digits in the reference (although not all 16 of them) so I
> always use an external reference.
> >>
> >> When I turn the PRS-10 upside down the crystal changes frequency and
> the Rb corrects the crystal, see:
> >> http://www.prc68.com/I/PRS10.shtml#Accel
> >> http://www.prc68.com/I/Images/FC_ROT.jpg
> >>
> >> Mail_Attachment --
> >> Have Fun,
> >>
> >> Brooke Clarke
> >> http://www.PRC68.com
> >> http://www.end2partygovernment.com/2012Issues.html
> >> http://www.prc68.com/I/DietNutrition.html
> >> Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> >>> On 27 November 2014 at 22:15, Brooke Clarke <brooke at pacific.net
> <javascript:;>> 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.
> >>>
> >>>> 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.
> >>>
> >>> I see one of the SR625 add-ons on eBay,
> >>>
> >>>
> http://www.ebay.com/itm/STANFORD-RESEARCH-SYSTEMS-SR625-2GHz-PRESCALER-/281486714451?pt=US_Marine_Aircraft_Radios&hash=item4189ea6653
> >>>
> >>> but it does not look in good condition, so I'm not paying $700 for it.
> >>>
> >>> Dave
> >>> _______________________________________________
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> >>>
> >>
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> >
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