[time-nuts] 100 MHz decade divider

[rfnuts]

Hi Perry,

this kind of frequency difference multiplyer is great for frequency 
adjustments, but has limited ADEV measurement performence.

If you're shooting for ADEV, symmetry of both channels, reference and 
DUT is inalienable. I have a Tracor 527 and Adret 4110. Both are way too 
noisy and drifty for ADEV.

The Quartzlock A7 and A7A are the by far best examples I know of. I have 
the manuals and some papers discussing key details, block diagrams 
included, though without schematics. Shoot me a mail if interested.

I have an A7. My DMTD has a lower ADEV noise floor than the A7. Each of 
them has its pro's and con's.

Btw. I'm looking for a 100MHz decade divider and PLL for 100MHz, just 
never got past collecting divider datasheets. I'd much appreciate to get 
a schematic if you like to share once finished.

Regards,
Adrian


Am 30.11.2019 um 00:50 schrieb Perry Sandeen via time-nuts:
> Yo Bubba Dudes!,
> I'm considering attempting  making a 10 MHz frequency difference meter sort of based on the Ticor 527.
> The design calls for using 100 MHz OCXO's and using the PLL difference to steer the EFC and then mix it with a PLL 90 MHz locked to the reference 10 MHz.  Then that 10MHz difference is fed into the next stage PLL and the process repeated in the following stages.
> Hy problem is this.  The only generally available 100MHz decade divider I've found is the 74LS196N.
> The problem arises that on the TI website it's advertised as going to 100 MHz BUT when one reads the data sheet it says that it only works to 85 MHz or so.
> I found on ebay the MC12080 100 MHz to 1.1GHz chip that can be configured to divide by 10.
> Now the ON units carried by the big name distributers are about $6.  The Chicom no-brand-name units on ebay are less that $2 each.
> I'd really like to use the LS296 chip as it is a dip type and *genuine* ones sell for less than $2 on ebay.
> Since I need one OCXO for each decade stage plus one for the 90 MHz reference, at $50 each used on ebay this starts to get very expensive quickly.
> I did find some obscure 100 MHz decade counters on some design circuit on the net but I'd never heard of them and expect they will be unobtainum.  The same seems to be true for the 74S and 74AC series.
> 
> So will the LS196 chip work reliably at 100 MHz or am I stuck with the MC 12080 or is there a better chip that I could use?
> Regards,
> Perrier
> 
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