[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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