[time-nuts] SRS SR620 External Source Issue -- Help Request

TheInfamousFlavio at hotmail.com TheInfamousFlavio at hotmail.com
Wed Feb 21 23:13:08 UTC 2007


I've done the self calibration. Nothing changes.  I've let everything 
warm-up and checked both channels A and B, same thing.  I've swapped the 
cables on the front and the back, same thing.  I've tried a T-connector on 
the ref input with 50ohm termination, same thing.

The readings are pretty stable, they are just offset by -0.0015 Hz.




----- Original Message ----- 
From: "Brooke Clarke" <brooke at pacific.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Wednesday, February 21, 2007 18:04
Subject: Re: [time-nuts] SRS SR620 External Source Issue -- Help Request


> Hi Flavio:
>
> Have you tried using averaging?  The right most digits are from an
> interpolator and if  you check the manual the displayed resolution is
> much greater than the accuracy, but if you average say 1,000 readings
> then those digits get much better.  Also have you done the self 
> calibration?
>
> Have Fun,
>
> Brooke Clarke
>
> w/Java http://www.PRC68.com
> w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
> http://www.precisionclock.com
>
>
>
> TheInfamousFlavio at hotmail.com wrote:
>
>>I have an SR620 counter that I set up with a Z3801A as an external 
>>reference.  If I put a bnc T connector at the output of the Z3801A and use 
>>two equal length bnc cables, one to the ext. ref input on the back and the 
>>other to channel A then do a frequency measurement, I get a mean that is 
>>about .0015 Hz below 10,000,000.0000Hz.
>>
>>Does any know why this might be happening? I would expect it to read 
>>10,000,000.0000 exactly give or take a couple on the last digit.
>>
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>>
>
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