[time-nuts] DIY Frequency extension for HP Agilent 53181A, 53131A or 53181A

Richard H McCorkle mccorkle at ptialaska.net
Sun Feb 15 19:01:59 UTC 2009


Hi Samuel,

I suggest starting by downloading the component level information for
the 53131A and 53132A from tha Agilent site at the following links.

http://cp.literature.agilent.com/litweb/pdf/5989-6308EN.pdf
http://cp.literature.agilent.com/litweb/pdf/5989-6307EN.pdf

The 53132A document includes a schematic of the channel C board with
parts list and may assist in getting you started.

Richard


> Thanks for your answers.
>
> About the components, I think my first prototype will use some very
> well-known prescaler and amplifiers like Hittite HMC363 and Mini-circuits
> ERA-1SM, only to validate the design. I will use a 100 MHz high-pass filter,
> but overall, it will be a wide-band, low-sensitivity design, exactly like
> the original option.
>
> But before thinking about the best components to use for the amps and the
> divider, we need to know how to interface the prescaler with the counter.
> There is some very important questions to answer :
>
>  - What's the divider ratio used ? Perhaps /16 for 3 GHz, /32 for 5 GHz, and
> /64 for 12.4 GHz, but we really need to be sure.
>  - What's the gain of each one of the four amplifiers present ?
>  - How does the counter aware about the option used ? There is no
> "intelligence" on the option board, so, the counter may detect the type of
> prescaler with some pull-up or pull-down resistors somewhere.
>  - What is the exact pinout for the J2 connector ?
>
> In order to get an answer, we need to find somebody with a genuine option
> board willing to spend an hour for the project...
>
> :-)
>
>
>
> -----Message d'origine-----
> De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
> part de Rick Karlquist
> Envoyé : dimanche 15 février 2009 03:47
> À : Discussion of precise time and frequency measurement
> Objet : Re: [time-nuts] DIY Frequency extension for HP Agilent 53181A,
> 53131A or 53181A
>
> Max Skop wrote:
>> Hi Samuel and all,
>> Welcome to the group.
>> I also have a 53131A and would welcome any way to enhance or upgrade the
>> performance of this instrument. Please count me in on clone option parts.
>> As can be seen from the picure of the 3Ghz option there is nothing special
>> in its construction.  Just four stages of amplification and a divider.
>
> In 1987, I was the project manager for the HP 5334B frequency counter.
> In those days, we had a 1.3 GHz option called a "C channel".  I
> evaluated various off the shelf dividers at the time and built
> some C channel boards very similar to the one you are describing.
> It is actually very difficult to make a prescaler that really works
> well using off the shelf dividers.  The prescaler tends to be insensitive
> to low frequencies.  Attempting to fix this with a lot of gain
> (4 stages!) has the problem that any wideband noise from the source
> is also amplified.  Off the shelf dividers are made to work in
> frequency synthesizers where they have a clean signal from an oscillator.
> They don't do well with general signals from noisy sources.
> The HP 5386 used an HP made frequency divider that had "static"
> flip flops instead of the "dynamic" ones in all the off the shelf
> dividers.  It is the only prescaler I am familiar with that actually
> works well.  The custom IC in it cost HP a fair amount just because it
> was "home made" in the Santa Rosa fab, which was a money sink.
>
> If you want to build your own prescaler, you might not want to copy
> the Agilent one.  Unless you need the sensitivity, you would be
> better off with less gain.  Also, you should choose a divider that
> works well at the frequency you want to measure.  AFAIK, all OTS
> dividers have an optimum frequency range, which varies from divider
> to divider.
>
> When testing prescalers, the thing to watch out for is that the
> lower order digits will bounce around.  This is usually a symptom
> of prescaler error, assuming that the source is stable.
>
> Rick Karlquist N6RK
>
>
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