[time-nuts] Question for any HP105 owners HP5370 Settings

[Paul A. Cianciolo]

John,
Here is how I am set up currently with the HP 5370B,
I didn't understand the triggering comments you made preciously

1) Under    Function
 The counter is in the "TI" mode 

2) Under statistics  mode 
The counter is in the "Mean" mode

3) Under Sample Size
 Number "1" is selected

4) Under arming 
The "+TI" button is selected.

5) Under display rate.
Fully clockwise  the display nor the GPIB interface will update if this is
in the "hold" position

6) Inputs section
All three pots are in the "preset" position.
 10 MHz Z3801A Reference is connected to "Start"    DUT is connected to
"Stop
Start Stop inputs are "positive slope"  and each is "50 Ohms" Termination
Both input switches are in the "divide by 1 " position.
 External BNC has no input.

External reference drive, in the back = the Z3801A

LED displays " 53.20  with the. 20 changing  N secs"
Remote led lit 
"Talk"  in the GPIB area is lit.

Thank You for any help.



Paul A. Cianciolo
W1VLF
http://www.rescueelectronics.com/

"Time is relative"  Abert Einstien circa 1950
"Relatives use up all my time"  Lisa Cianciolo circa 1983


 



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Miles
Sent: Tuesday, August 30, 2011 1:25 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Question for any HP105 owners

> Right, the averaging time, tau, is critical when quoting ADEV numbers. 
> In fact, the key feature of any ADEV plot is seeing how stability 
> changes as a function of tau. But Mark mentioned "at 100 seconds" so 
> that allowed me to compare his single ADEV number against the tau 100 
> second column of a full log-log plot.
> 
> Your data looks odd to me. Sample rate, or bandwidth, can have a 
> noticeable effect for short tau but I would expect that by the time 
> you're all the way out to tau 100 s that the points would be about the 
> same. Instead in your case they differ by an order of magnitude.

Are you (Paul) using the counter in frequency mode, or are you using a
1pps/10pps divider?  The 5370 is noisier in frequency mode, and there's also
some dead time.  The best way to use the 5370 to compare two 10 MHz
oscillators is probably to use +TI mode with the sources applied directly to
the start and stop channels, and trigger the counter at 1 pps (or 10 pps)
with a divider.  I usually don't bother with the external trigger but I do
use TI mode over frequency mode if I actually care about ADEV fidelity.

-- john, KE5FX
 


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