[time-nuts] SR620 calibration
jfor at quik.com
Sun Feb 27 21:27:10 UTC 2011
And the schematics? I've tried without success.
Repairing hardware w/o schematics is pretty tough.
> Regarding the SR620 counters, I must have missed something.... It
> seems to me that SRS is providing about as much support as Tek or
> Agilent. All three offer PDF manuals and repair service. I doubt any
> of them have free telephone repair support for out-of-warranty
> I did a Google search for "stanford research sr620 manual pdf" and it
> returned a number of sites, including SRS and NASA, that had the SR620
> manual available for free download in PDF format. I had looked for
> that manual several years ago and found it then too. I did a quick
> compare against the paper copy of the manual and it seems to be
> similar although I will not say exactly the same since I didn't look
> that close.
> Since the manual has full directions for using the counter and for
> doing calibration, I don't understand the comments that SRS doesn't
> support the product and make the info available. The schematics are
> not included in the PDF manual but that is true of most electronic
> products. I expect my paper manual has them although I haven't
> Regarding the cost of repairs, I don't care what company you talk to,
> they are ALL too expensive for me. But since I didn't buy the
> equipment new with a warranty I don't see where that is their problem.
> I bought my car out of warranty and I don't expect the dealer to do
> repairs for cheap. I have several pieces of test equipment that were
> labeled "Not Economical To Repair." That is why they were in the scrap
> bin. But they work good enough for me to use as long as I can live
> with the fault.
> I do like the counter even though I've never used any of the advanced
> features it has. My only complaint was the 10^-6 accuracy of the TXCO
> reference oscillator but since I can calibrate it at will and can use
> my Z3801A as an external reference, I can live with that. Somewhere
> along the line I need to do some research or get one of the gurus on
> the reflector to explain how to use the SR620 for doing Allen variance
> and other quality checks of the various GPSDO, rubidium, and OCXO
> oscillators I've collected in recent years. That is about the most
> advanced feature I need from the SR620.
> I probably don't qualify as a real time-nut since my main interest is
> to get my 10GHz station within a few hundred Hz of 10368.100 MHz. A
> few parts in 10^-11 is good enough for that..... And I would like to
> compare my various reference oscillators just to verify they are
> working as well as can be expected. But that doesn't make me a REAL
> time-nut.... :-)
> I don't intend to rekindle the previous discussion, I just don't
> understand the negative comments. I have several SR620 counters and
> for a 1GHz counter I think they are pretty good. For higher
> measurements I got lucky on eBay purchasing an EIP 25B counter that
> seems almost new. I didn't get as lucky with the HP 5340A I bought
> first. Expensive and unobtainable mixer parts make the 5340A
> I do enjoy the technical discussions on the list. I particularly liked
> the discussion about rejuvenating a rubidium lamp. The N4IQT web page
> mentions the procedure but the time-nuts discussion provides a lot
> more detail. That should be added to a web page somewhere along with
> long term measurements of the results to indicate how the fix is
> holding. I'm sure there are a lot of people who would be interested in
> extending the life of their old rubidium oscillator. Having that info
> would certainly make me sleep better if buying a surplus rubidium on
> 73, Doug Reed, N0NAS.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
More information about the time-nuts