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

[Richard (Rick) Karlquist]

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."  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.

Rick

I remember those dynamic divider
> circuits used in the old days to make 1 MHz and 100 kHz from 5 MHz, or 
> the more modern kind based on mixers, filters, and amplifiers, to say 
> make 5 from 10 Mhz, but I'm pretty sure I have never seen a 
> VHF/UHF/microwave prescaler IC that was not completely static - they are 
> chains of flip-flops and logic, pure and simple. The way they are 
> typically used may hide their nature a bit, but they are fundamentally 
> static counting machines.
> 
> Perhaps we have different definitions for dynamic vs static. My 
> definition of static is that there's a unique, stable machine state for 
> each possible count value, and you can stop it at any count value and 
> restart it, with the right logic activity, over any period of time. The 
> "right logic activity" would be to take logical control of the inputs 
> rather than set them up for counting RF directly in an analog 
> self-biased mode. In other words, you could put a gate in front of the 
> input to control the counting.
> 
> For instance, in the data sheet for the HMC493 it says in the General 
> Description:
> 
> "The  HMC493LP3  &  HMC493LP3E  are  low  noise
> Divide-by-4 Static Dividers utilizing InGaP GaAs HBT
> technology  packaged  in  leadless  3x3  mm  QFN  sur-
> face  mount  plastic  packages.  This  device  operates
> from  DC  (with  a  square  wave  input)  to  18  GHz  input
> frequency from a single +5V DC supply."
> 
> The part about operating at DC "with a square wave input" means at the 
> normal logic levels of the device, I'm pretty sure. And usually there's 
> a minimum toggle edge speed for the various logic types, so there is a 
> little bit of dynamic-ness there, if you were to try to count at very 
> low rates.
> 
> Ed
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