11/8/2012 - sold out - consider the Prescaler "X" kit as an alternate.
The kit includes the 5 volt regulator, two .1 uf bypass capacitors, two
1000 pf coupling capacitors, a 51 ohm input resistor and an 820 ohm
output loading resistor along with an MC12080 prescaler and the circuit
board. The passive components are 1206 sized while the prescaler
is in an 8 pin SO package - these are both relatively easy to
solder but the kit is not for surface mount kit beginners.
The circuit board is about 1.3 by 0.7 inches and has
one mounting hole sized for 4-40 hardware (1/8 inch).
The prescaler kit is a simple divide by 10 ECL circuit which can be
used to extend the range of most PIC based frequency counters from
50 MHz up to 500 MHz. The kit uses surface mount components except
for the 78L05 regulator.
Printed manuals available for an additional charge or
save money by downloading (Right click/save target as)
and printing the prescaler kit
and hookup diagram
all in Adobe Acrobat (.pdf) format.
Is it normal for the prescaler to output a frequency when the
input is unconnected ?
Yes, my prescaler does this at roughly 20 MHz.
If this bothers you, Earl, N8ERO, suggests this fix, add a 100 k ohm
resistor across capacitor C1. This results in slightly lower sensitivity.
What is the sensitivity of the prescaler ?
Here is some
customer measured sensitivity data.
For any questions, please send an email to me, Chuck Olson, WB9KZY at: