Joe,
     I found the PIC that is being used to control the reset, latch, and=20
gating signals. If this works it will be a lot more flexible then the=20
discrete chips in the time base. I should be able to measure frequencies=20
down in to the mHz range and up to 100MHz with 1Hz resolution of any=20
frequency from 1Hz upward to 99,999,999Hz. I can also use the PIC to=20
automatically set the decimal point. The 390 decade counters that I am=20
using have operated at 100MHz with no problem. I will also be able to=20
eliminate two transistors, several resistors and capacitors, a 4060, two=20
390s, a 90 counter, a 4053 multiplexer, and all of the associated wiring=20
and I won't need the discrete chips needed to generate the reset, latch,=20
and gating signals. I will need the crystal but I'll use a resonator=20
instead and I may go to a canned osc. Add some switches and I can also=20
blank the leading zeroes with a little extra programming and wiring. I=20
can also automatically switch a prescaler in and out which would allow=20
the counter to operate in to the GHz range. By not using the PIC to=20
actually count the frequency I am bypassing the 50MHz limitation. Hum=20
this sounds more and more interesting.
Thanks,
rich!

On 6/23/2014 8:29 PM, IVP wrote:
>> Using just the divider stage of a PLL IC you can go up to several GHz
> Just out of interest -
>
> The 2.5GHz FM I mentioned uses the MC12095 ( /4), MC10E016
> ( /125) and MC10EL32 ( /2) to divide the incoming signal frequency
> by 1000 on the 100MHz - 2.5GHz channel. The initial front end amp
> is an ERA-25M+
>
> http://www.ges.cz/sheets/e/eraxx.pdf
>
> The /1000 puts the least-significant decades speed well within the
> range of a 16F877, as there's been a further /10000 by the counters
> for the first 4 decades
>
> Joe

--=20
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