Thread: Homebrew GPSDO
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Old 5th Mar 2021, 9:57 am   #12
Radio Wrangler
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Location: Fife, Scotland, UK.
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Default Re: Homebrew GPSDO

Only 2Hz low 5 mins after cold turn on for you OCXO is rather good. The HP 10544B can be around 1kHz low stating at 22C room temp. The 10811A SC cut one is similar. These are at 10MHz so that's an error of -100ppm!

The reason is that quartz intended for 80C oven use is cut to give the flattest frequency/temperature slope at that temperature. So the curve is parabolic, centred on 80C and room temp is a long way down the cold side slope.

These oscillators, at switch-on, are a lot further off-song than TCXOs. But people do tend to assume they're always better and consider frequency error inconsequential in anything with the OCXO option, right from pressing the 'on' button.

David
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