[time-nuts] Re: [OT] MB506 pre-scaler module ??

[Lux, Jim]

On 5/13/23 9:02 AM, Richard (Rick) Karlquist via time-nuts wrote:
>
>
> On 5/12/2023 6:00 PM, ed breya via time-nuts wrote:
>> Rick, I don't see how you have the impression that any of these 
>> prescalers are "dynamic" dividers. \
>
> That is what the project manager of the HP 5386 told me back in
> the 80's.  He used a static divider made by HP Santa Rosa.  The
> 5334A used a dynamic divider made by HP Santa Clara.  As the
> 5334B project manager, I tried whatever COTS dividers I could
> find and they all had the same problems as the divider made
> in Santa Clara.  I designed that one out to save $100.
>
> You previously said something like any prescaler will work if
> the signal is coming from a signal generator.  This notion is
> contradicted by the HP 8660.  For both the 5334A and 5334B,
> the test procedure for the C channel is to drive the counter
> with an 8660 at 1.3 GHz to verify the specified bandwidth.
> However, the TP goes on to say that a 1 GHz high pass filter
> must be inserted in front of the counter.  And sure enough,
> if you don't do this, it won't count 1.3 GHz.  Admittedly,
> the 8660 was not exactly what you would call HP's "finest
> hour."Â  I suspect you could dispense with the filter if you
> used an 8662/3.
>
> I was not aware of the HMC493, which seems to be static.  With
> that chip you might finally be able to homebrew a decent C channel.
> The description of the technology used sounds like something
> that would come out of the Santa Rosa IC fab.  The price is a
> bargain IMHO at $35.  For $425 you can get an eval board.
> So it looks like the technology has advanced somewhat in
> 35 years. 


Hittite (HMC) made a bunch of GaAs dividers (and some are still being 
made) that worked up at microwave frequencies.  Some of them were 
originally developed under SBIR funding from NASA.  We use them in 
synthesizers for deep space radios.  We were trying to get wideband 
(50-100 MHz) tuning coverage at X-band, and our ideas with DROs with two 
varactors didn't work out.  So we went to MMIC VCO and dividers in a 
conventional PLL sort of arrangement (as opposed to DROs and SPDs)

https://ipnpr.jpl.nasa.gov/progress_report/42-166/166A.pdf

describes the approach and measured performance in the application 
(using eval boards). I can't remember what parts we used for the divide 
by 8 and the divide by N, and the picture is too low res to read it off 
the part.  I can probably find it. (Oddly, I think I saw these 
breadboards a couple years ago in a closet).


The Iris cubesat transponder uses a divide by 2 like the HMC361 from 8.5 
GHz or 7.1 GHz

https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=3603&context=smallsat

It's true that in these applications, the divider is seeing only one 
signal with very good SNR - it's not like a general purpose counter.


As far as I know, they're just a chain of flipflops, sometimes with some 
logic (there was a variable divide ratio one we used). They aren't 
exactly low power.