On May 4, 2014, at 9:51 PM, Jean-Paul Louis <louijp@yahoo.com> wrote:

> Tom,
>=20
> The pre-scaler is great, but you still need an amplifier or a comparator =
to reach the safe zone of the pre-scaler, 0dBm +/- 5dB for signals below 20=
0MHz.
> This pre-scaler might not work with a signal from -25dBm to -5dBm. it wil=
l need an amplifier with a gain of ten or better twenty, which can be done =
with a single transistor.
>=20
>=20
> Jean-Paul
> AC9GH
>=20
>=20
> On May 4, 2014, at 9:13 PM, Thomas Sefranek <wa1rhp@comcast.net> wrote:
>=20
>> Think pre-scaler=20
>>=20
>> http://www.onsemi.com/pub_link/Collateral/MC12080-D.PDF
>>=20
>>=20
>>=20
>> On May 4, 2014, at 8:41 PM, Martin K wrote:
>>=20
>>> I want to divide an RF signal down from 100 MHz to something between 1=
=20
>>> and 5 MHz for precise counting.
>>> The RF is essentially CW with a bit of frequency modulation. Signal=20
>>> power is -5 to -25 dBm which corresponds to a voltage on a 50 ohm load=
=20
>>> of 12.5mV to 125mV.
>>>=20
>>> My plan is to use a very high speed comparator to capture the (AC=20
>>> coupled) zero crossing and put the output (LVPECL) into a couple 1:8=20
>>> dividers in series. The signal will probably end up going to an FPGA so=
=20
>>> LVDS or LVCMOS is desirable.
>>>=20
>>> Is there a better way?
>>>=20
>>> Thanks,
>>> Martin
>>>=20
>>>=20
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>>=20
>> *
>> |  __O    Thomas C. Sefranek  wa1rhp@comcast.net
>> |_-\<,_   Amateur Radio Operator: WA1RHP
>> (*)/ (*)  Motorcycle mobile on 145.41 MHz.
>>=20
>> ARRL Instructor, Technical Specialist, VE Contact.
>>=20
>> http://www.harvardrepeater.org
>>=20
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>=20


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