[time-nuts] Measuring Phase diference between different GPSDO

Mark C. Stephens marks at non-stop.com.au
Thu May 2 23:35:10 EDT 2013


After unscrewing the great stack of (no longer used) GPIB cables, I noticed the wee switch on the back was set to external reference with no external reference plugged in!
Switching this to internal, the timer burst into life.
We have green to go on the 5370B, Houston!

mark

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Mark C. Stephens
Sent: Friday, 3 May 2013 1:09 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Measuring Phase diference between different GPSDO

It is as you said Bob, I plugged the 5370b in and It flashed a zero then the display and front panel are blank.

It has some other equipment in service on top of it so when I get a chance for some downtime, I'll pull it out and reseat the boards.


Wish me luck!


mark

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
Sent: Friday, 3 May 2013 11:42 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Measuring Phase diference between different GPSDO

Hi

FIrst step is to fire up the 5370B counter and see if it works. If there's a problem re-seat all the boards and see if that fixes it. Simple way to check it is to let it count it's own reference. 

Once you have that working, then yes, measuring time between PPS outputs is the way to go. 

-------

Assuming it is beyond help, then the PicTic counter board is a reasonable alternative. It will also let you measure between PPS's very accurately. 

Both approaches are far more accurate than you will need for checking conventional OCXO based GPSDO's

Bob


On May 2, 2013, at 9:33 PM, Mark C. Stephens <marks at non-stop.com.au> wrote:

> I'd like to perform some comparison between a known good GPSDO and some newcomers.
> I want to adjust the crystal turning point as my new GPSDO tend to wander all over the place.
> I see some of you are using the hp 3575A to do this.
> 
> Unfortunately, they are a little out of my price range at the moment.
> 
> What I do have is a an ancient hp 8407a with both 8412a and b Phase magnitude display and a 8413a phase/gain indicator.
> Is there any way they are usable to achieve the desired measurement?
> 
> A also have a hp 5370b timer. I am not sure if it still works, but anyway, would measuring the PPS be an easier option?
> 
> I also hear mention of a PICTIC, what is that?
> 
> 
> Many thanks,
> Mark
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