Thursday, April 5, 2012

Stable Propeller Clock

Well, I obtained a nice temperature compensated 10 MHz clock for my propeller board, courtesy of Eldon WA0UWH.  Here you can see the little daughter board that Eldon designed.  The normal 5 Mhz crystal has been removed and the software adjusted to set the system clock at times 8 instead of times 16, so we are still running at 80 MHz.

After spotting it on 10.140.200 MHz I captured my WSPR decode and as you can see in the last spot after touching up the pot a little, I am spot on frequency (10.140.200) and zero drift.  Yeah!  The waterfall display shows me swinging the pot through its range over several samples.

The board has a nice, though a little touchy pot to net the frequency where you want it.  It currently has a range of about 100 Hz.  In the final version, I think this will be tweaked to slow the tuning down to about 1/2 that amout or so.  Once adjusted it stays put and doesn't seem to be affected by temperature as expected.

The oscillator output looks like this:

So, I am quite pleased with this little modification to the propeller proto board.

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