Hi David:

If you look just to the right of the SR620 you will see a separate box that contains the PRS10.

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.
http://www.prc68.com/I/LTE-LiteGPSDO.html#Related

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:

Hi

Given the relatively short life of some Rb’s and their usefulness as a reference for many things … better to have the 620 and an external Rb.

Next level is that Rb’s run pretty hot (lots of power). The 620 already is a bit warm inside. Adding even more heat does not sound very attractive.

Bob

On 27 November 2014 at 22:15, Brooke Clarke brooke@pacific.net wrote:

Hi Brooke

Ah, I missed that!!!

I was thinking it fitted inside the SR620, but obviously not.

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

David,

On 11/27/2014 11:37 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:

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

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.

Cheers,
Magnus

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:

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.

Prescalers from RFBay.

Don

Hi

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

On 28 Nov 2014 02:06, "Don Latham" djl@montana.com wrote:

adding a 7812 to the 15 v heater

Did the SR620 have option 01 before you did the mod?

In other words,  did you change to the Moxen because you believe it is
better than Stanford Research's high stability, or just because the SR620
had the TCXO?

Will the 7812 not add noise? There are lot lower noise devices around,  but
I guess if it only powering the oven, it is not important

I am still waiting to hear my SR620 has been dispatched.

Dave.

Hi Dave:
My 620 arrived with option 01, but the ocxo was out of tolerance and I could not bring it to 10 MHz. So I adapted a Morion that I had on hand.  The self-test passed, but of course there is no way to self-test the frequency of the internal standard. I may open up the original osc or not.
The noise should be ok, there is another regulator for the works in the ocxo.
If the 620 did not have 01 option, a morion could easily br installed according to the schematics, I think.
Don

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@n1k.org wrote:

On Wed, Dec 3, 2014 at 12:08 PM, Neil Schroeder gigneil@gmail.com wrote:

I took the easy way out and bought the interface board (directly from SRS).

On Wed, Dec 03, 2014 at 02:53:50PM -0500, Paul wrote:

Do you have any rough number as to what they charged you for

this ?

--
Dave Emery N1PRE/AE, die@dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."

I am convinced it's a grounding problem as well but I'm overly paranoid
about frying my not-cheap oscillator experimenting with it if others had
experience.

I went through a couple of them prior to getting one with a fully
functional photo acquisition system so I wasn't gonna quibble over a few
bits on a serial interface when the oscillator obviously work.

On Wednesday, December 3, 2014, yDavidkk I. Emery die@dieconsulting.com
wrote:

On Wed, Dec 3, 2014 at 3:54 PM, David I. Emery die@dieconsulting.com
wrote:

The price at the SRS store is $150.  A great deal compared to $100 for a
manual or heatsink.
Granted the board is a bit more complex than a DE-9 and a couple of BNC
connectors. I just looked at the retail for a PRS-10 and got over it.

I certainly won't cry foul. There's places where rolling your own can put
key assets at risk - it I had 4 I would push the issue but I only have one
atomic reference and I'd rather not blow it up

If anyone has things they need blown up I am available for the cost of
beer. As electronics get more advanced and smaller they certainly have
become MUCH more delicate.

On Wednesday, December 3, 2014, Paul tic-toc@bodosom.net wrote: