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My latest BITX20A H&P stabilizer taps the VFO output at the junction of
R-27 and Q-6 collector (top of R-27 on the kit circuit board). I fed
the common point between H&P integrator caps to a 150K resistor that
connects to the junction of R-38 and D-9.
At present I am using the G8SEQ idea
of an intact watch unit providing 32 Hz reference with half a 74HC74 as
the latch. The other half of the 74HC74 is used as a buffer to square up
the VFO output.
The Ron Brink PA2RF circuit is probably a more elegant solution, but
this simpler method seems to work well enough for my needs.
Greg Derda wrote:
Thank you for the reply and info. I have considered a stabilizer, and
I have tried to learn more about them, but what is not clear to me is
where to tap the VFO for the output to, and input from, the stabilizer.
For example, if a person wanted to add one to the Farhan-circuit VFO,
where would you tap it?
On Feb 15, 2008, at 10:25 AM, Martien wrote:
--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, Greg Derda <gderda@...> wrote:
You could use the 10MHz standard with an 8Mhz VFO. This VFO can be
easily stabilised using a "Huff and Puff" circuit. There are many
examples on the web. I used this simple one (fig.1 schematic)):
VFO is rock solid, PSK 31 is no problem.
Text is in Dutch but the schematics are quite clear.