[time-nuts] SR620 calibration

[Jean-Louis Oneto]

I have a scan of the schematics (A3 format), but it is rather heavy (3.6MB); 
Do you know of a place to store such a beast ? I have also a copy of the 
manual it self, but that's easier to find (I got mine from the SRS web site)
Have a nice day,
Jean-Louis Oneto
France
e-mail: Jean-Louis.Oneto at obs-azur.fr

----- Original Message ----- 
From: "J. Forster" <jfor at quik.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, February 27, 2011 9:27 PM
Subject: Re: [time-nuts] SR620 calibration


> And the schematics? I've tried without success.
>
> Repairing hardware w/o schematics is pretty tough.
>
> -John
>
> ===========
>
>
>> 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
>> products.
>>
>> 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
>> checked.
>>
>> 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
>> unrepairable.....
>>
>> 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
>> eBay.....
>>
>> 73, Doug Reed, N0NAS.
>>
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