[time-nuts] FTS 1050A
ed breya
eb at telight.com
Tue Aug 9 21:05:12 UTC 2011
If you just want to get it to an integer value, I recommend, for
example, that you find or make a 6.0000000 MHz VCXO using a common 6
MHz crystal, and mix it with the 6.000300 MHz using a 74HC86 XOR,
then the 300 Hz IF can easily be low-pass filtered out and used as
the feedback to a PLL (like 74HC4046A) which drives the VCXO. The
other input to the PLL can be made by dividing the VCXO output by
20,000 (with 74HC390s), resulting in 300 Hz as a reference. The net
result is that the ovenized oddball reference will phase lock the
common-frequency VCXO - but only close-in since the sample frequency
is only 300 Hz - farther out phase noise will depend on how clean you
make the VCXO. Once you get 6.000000 MHz, you can make whatever you
want. With a little more complexity there are lots of combinations
that could make a nice integer value (like 10.000000 MHz), and at a
higher sample frequency - you just have to figure out what you can
add, subtract, multiply and divide with convenient values to get
something usable.
Ed
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