[hpsdr] Reference Clock Information

[Christopher T. Day]

Chuck,

There was an interesting article in the AmQRP Homebrewer Magazine #6
entitiled "The TC908 Temperature Controller or ... Taming the Atlanticon
2005 Crystallizer". Evidently, the Atlanticon 2005 challenge was to
build the simple Crystallizer VCXO kit and stabilize it against
temperature changes however possible with a bake-off, more-or-less
literally, at the convention. Steve Holton, N1NB, won with this project
using the Micro908 inside an Antenna Analyzer 908 to read a thermister
in a box with the Crystallizer and adjust the control voltage
accordingly. He made the calibration curve with an ice chest and
thermometer. He used an SPI Digital Potentiometer to adjust the control
voltage. In the end, he apparently achieved < 0.1ppm over a hairdryer
temperature range. I suppose the close in phase noise and the like
wasn't great as it was a cheap crystal, but it might make an alternative
approach. It's hard for me to imagine that a great deal of computing
resources are needed to control this; maybe the 8051 in Ozy's FX2 would
do? Anyway, just a thought.


	Chris - AE6VK


-----Original Message-----
From: Chuck Clark [mailto:af8z at panaband.com] 
Sent: Monday, June 05, 2006 4:31 AM
To: hpsdr at hpsdr.org
Subject: [hpsdr] Reference Clock Information

***** High Performance Software Defined Radio Discussion List *****

Clock Oscillator Selection Guide

...

TCXO

Temperature compensation of a VCXO. This improves the temperature drift.

Possibly useful in a hold over mode.

...

The TCXO is characterized by the ability to hold the frequency range to 
within x parts per million (ppm) over a specific temperature range. 
Wider temperature ranges usually have wider frequency windows.

...



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