[time-nuts] frequency sources

Don Latham djl at montana.com
Fri Oct 16 02:20:24 UTC 2009

Some list members indicated a need for a well-controlled easily set
frequency source. Another list I get has to do with software defined radio
(softrock40). A member of that list mentioned a Maxim chip, the DS1077
oscillator/divider. The chip plus breakout board is close to ten bucks
from Sparkfun. This chip will put out two frequencies and is I2C
programmable. Over its temperature range, it is goodto +- 1.4% of its
fundamental frequency.

Suppose one of the outputs is set to 10 MHz nominal. Now put a very small
thermoelectric cooler stinger on it and put that in an insulated housing
with heatsink outside. Connect a very simple comparator to your rock solid
10 MHz and the 10 MHz from the wonder chip. Hook this to a cheap PIC with
suitable pwm to the thermoelectric cooler. Hey presto, a sort of OCXO with
one adjustable frequency left. Can it work? I haven't time to try it now,
but who knows...

Dr. Don Latham AJ7LL
Six Mile Systems LLP
17850 Six Mile Road
POB 134
Huson, MT, 59846
VOX 406-626-4304

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