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

Bob Camp kb8tq at n1k.org
Thu Nov 27 17:30:52 EST 2014


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. 


> On Nov 27, 2014, at 4:06 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
> I finally paid for a used SR620
> http://www.thinksrs.com/products/SR620.htm
> today, after the seller has done quite a few tests on it, so hopefully
> I should have a good one.
> I note Stanford Research also do an SR625
> http://www.thinksrs.com/products/SR625.htm
> which seems to have two differences
> a) It uses a PRS10 timebase
> b) Has a 2 GHz pre-scaler.
> I wonder if anyone has tried fitting a PRS10 into an SR620 to make it
> close to an SR625? I'm not too fussed about having 2 GHz, as I just
> bought a nice condition HP 5342A microwave (18 GHz) counter. But I
> would be interested in fitting an Rb source in the SR620.
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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