[time-nuts] 3GHz prescaler for Pendulum counters
GandalfG8 at aol.com
GandalfG8 at aol.com
Sun Nov 15 06:11:03 EST 2015
Hi Arthur
Thanks for the feedback, that's an interesting find and obviously
something to keep in mind.
As you know Pawel originally designed the prescaler for the CNT85/PM6685,
although in earlier Ebay listings he did comment that it also worked for
the CNT80/PM6680, and taking a look at the schematics I can see now that the
detection circuit you refer to for the CNT81 is different to that in the
CNT80 and also to that in later models.
In the CNT80 the selection resistors were returned directly to ground,
that 100K common resistor was introduced with the CNT81 but was promptly
dropped again for the CNT85 onwards.
It would seem, in this respect anyway, that you drew the short straw:-)
Interesting too to see your comments regarding orientation, although from
the CNT85 onwards this again seems to have been something that was
standardised.
Glad to hear you got it sorted though, I'm still more than happy with mine
and certainly agree that it's a really good deal.
Regards
Nigel
GM8PZR
Just a note to say that I bought one of these
prescaler boards for my CNT-81. One problem is
the way the board mounts in the CNT-81 the "in"
connector is toward the back instead of toward
the front like some of the other counters and I
had to make a longer input cable. Pawel does
now know this and maybe a different cable can
be included for these counters in case you can't
make one. Be sure to check on this so there
aren't any surprises.......
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