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

Don Latham djl at montana.com
Wed Dec 3 10:50:57 EST 2014

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.

> On Dec 3, 2014, at 8:39 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
> On 28 Nov 2014 02:06, "Don Latham" <djl at montana.com> wrote:
>> I’ve just replaced the SR620 oxco option 01 with a Morion, by simply
> 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.
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