[time-nuts] 9390 GPS RX

Mark C. Stephens marks at non-stop.com.au
Thu May 30 00:14:44 EDT 2013

Ah, The old Section 2 part (in Don Adams voice)

Okay, I have been watching the timer out of the corner of my eye, and there is a trend.
The TI difference gradually falls down to about 3ns (good) then shoots up to 103ns (bad) and then slowly falls down to 3ns in just over an hour, it then shoots up to 103ns again and repeats the process.

This is why I get good readings for short term.

The frequency can't be out that much, surely?

Anyway, as you say, Put it in the 9390 and see if 9390 can phase-lock it.

That certainly will be interesting if it does!


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Ed Palmer
Sent: Thursday, 30 May 2013 3:31 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] 9390 GPS RX

On 5/29/2013 9:58 AM, Mark C. Stephens wrote:
> Uh, well. No one told me about the heatsink thing :)

Section 2 in the manual talks about mounting and heatsinking.  You mean you didn't read the flippin' manual??? ;)  Anyway, it's good that you were able to get it on frequency.

> I am using a HP5370B.
> I am comparing to my best GPSDO.
> For instance my 5x Z3805A's get down to the low -12's after 1 hour.

Remember what these measurements mean.  Result = sqrt(<measurement 
system>^2 + DUT^2 + Reference^2).  Your measurement system and reference
have to be significantly better than the DUT or they will affect the result.  The 5370B should be low enough to be ignored at these Tau values.  Your Z3805A should be okay, I think, but not by much.  My Z3801A happens to have a 'disciplining hump' that peaks at around 1000 sec. and was affecting the measurement at 800 sec.  I was also using a 5370B.

> 4.7e-11 at 1 hour 12 minutes.

Yeah, that's high considering that the monthly drift is supposed to be less than that!  Let it soak for a month and see what happens.

> Do you think the FRK is ready to go back in the 9390 :) I hope so, I 
> like that 9390 and I want it in my rack :)

Yes, I think so.  Like I said, see what monitoring capability the 9390 has.  I suspect that the FRK will improve over the next while. Only time will tell how much.

Congratulations!  It looks like your FRK is alive!  After a little time to work out the last few kinks it should be in good shape. (Knock on
wood!)  :)


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