[time-nuts] Question on HP5359 Time Synthesizer

Ulrich Bangert df6jb at ulrich-bangert.de
Mon Jun 23 13:49:02 UTC 2008


Poul, Bruce and Greg

thanks for your help. I see a lot clearer now! The manual can be
downloaded from Didier's manual web page 

http://www.ko4bb.com/cgi-bin/manuals.pl?dir=HP_Agilent

Best regards
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Greg Burnett
> Gesendet: Montag, 23. Juni 2008 10:56
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Question on HP5359 Time Synthesizer
> 
> 
> Ulrich,
> 
> Your HP 5359A observations are normal, and many other HP 
> 5359A users have 
> asked exactly the same question, down through all these years 
> since the box 
> was first introduced. The main point is that the HP 5359A's 
> purpose is 
> *only* to generate precise timing. The box wasn't intended to 
> generate 
> precise frequency because, in its 'frequency mode' it only generates 
> *approximate* rates by "kicking (triggering) itself in the pants" 
> repetitively. (Therefore it is *not* a frequency synthesizer and its 
> "frequency" is not phase-locked to its timebase.)
> 
> Interesting note: Despite fact that the HP 5359A is not designed to 
> synthesize nor lock its "frequency" to its timebase, if you set its 
> frequency for "10 MHz" it sometimes might actually 
> synchronize itself to its 
> 10811A timebase. This interesting effect only occurs at 10 MHz and 
> apparently is a sympathetic synchronization effect due to 
> ground loop and 
> proximity coupling between circuitry and the timebase 10 MHz 
> signal. ...This 
> is a very weak effect, is not by design, and, again, can only 
> occur for 
> frequency settings of exactly 10 MHz.
> 
> Cheers,
> Greg
> 
> -----------------------------------
> 
> Ulrich wrote:
> 
> Gentlemen,
> 
> some time ago I had the possibility to buy a surplus HP5359 
> Time Synthesizer. As far as I can judge from my measurements 
> with a HP5370 and a SR620 the two delays that are generated 
> inside the box with high precision are ok and completely 
> within the specs, which is the most important feature for me.
> 
> There is however one annoying fact: If I use the instrument 
> in "frequency" or "period" mode, where the negative slope of 
> the second delay generator is used to trigger the first delay 
> generator in order to generate a repetitive waveform, I 
> notice that a few moments after I have pressed the 
> "calibration" button (which should adjust everything
> automatically) the frequency of the repetitive waveform will 
> change and drift by an amount of some 100 Hz up to a few kHz 
> so that my counter may read 996 kHz after a few minutes with 
> the drift getting smaller over time as the device warms up.
> 
> I have first thought that this effect is due to a defective 
> 10811 in the box but the effect is the same with an 
> externally supplied standard frequency. Well, the thing is: 
> If one reads the manual carefully he will find out that there 
> is no spec about frequency stability to be found anwhere in 
> it! On the other hand the manual says to check the "trigger 
> assembly" in case of coarse "overall timing errors". The 
> trigger assembly is the point where the negative slope of the 
> second delay generator is feed back into the trigger circuit 
> to make the waveform repetitive. Am I complaining at 
> something completely Ok or should I have a deeper look to the 
> trigger circuits? Hopefully one of you 5370 adepts can give 
> some explanation.
> 
> Ulrich Bangert
> www.ulrich-bangert.de
> Ortholzer Weg 1
> 27243 Gross Ippener
> 
> P.S.
> 
> While I am writing this the drift rate has reduced to abt 1 HZ / sec.
> 
> 
> 
> 
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