Thread: Franklin VFO ?
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Old 15th May 2019, 7:38 pm   #30
G0HZU_JMR
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Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
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Default Re: Franklin VFO ?

Granitehill, have a quick look down the 'LO Noise' and the 'Spacing' columns in the link below. Most radios seem to be tested at a 10kHz offset (spacing) and there are quite a few radios that measure close to -100dBc/Hz at a 10kHz offset. That's probably 50dB worse than this little Franklin oscillator.

http://www.sherweng.com/table.html

I do think the phase noise of this oscillator will be close to -150dBc/Hz at a 10kHz offset but even if the -136dBc/Hz limit of the Tek RTSA analyser is used instead, it is still a lot better than the system phase noise of many HF transceivers of the last 30-35 years from Yaesu/Kenwood. The Yaesu FT One measures -99dBc/Hz at 10kHz offset for example.
I've added some scaling text on the frequency axis in the plot below to make it clearer where the 100Hz, 1kHz and 10kHz offsets are. The marker shows the phase noise is somewhere around -122dBc/Hz at a 933Hz offset.
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Last edited by G0HZU_JMR; 15th May 2019 at 7:50 pm.
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