[time-nuts] How can I generate a very clean 1 W signal @ 116 MHz ?

[Bob Camp]

Hi

There are a lot of published circuits for low noise VHF crystal oscillators.  At the offsets you are talking about the
phase noise is mostly a function of simple signal to noise. More power in the crystal == lower noise. You should 
be able to do better than -165 dbc/Hz with a little fiddling. Having a EFC that is wide enough to lock to 10 MHz
should not degrade the noise to badly. 

Since the crystal is not a big deal at wide offsets, a “buy some and see” approach is by far the lowest cost way 
to get the parts to use in the circuit.  Also since vendors change process from month to month, what you buy today 
may not be what you get a few months from now. Not a big deal for a one off. Likely a PIA for a production build. 

Bob



> On May 30, 2016, at 7:06 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
> 
> I was thinking about designing a 2 m (144-146 MHz) ->HF (28-30 MHz)
> transverter, using a 116 MHz local oscillator feeding a level 30 mixer.
> 
> 116 + 28 = 144
> 116 + 30 = 146
> 
> I'm wondering what's the best way to generate 116 MHz with very low phase
> noise. Phase noise at < 20 kHz offset is particularly important, but 200
> kHz would be fairly important. Outside that, it does not matter too much.
> 
> The ability to lock to 10 MHz would be "nice", but certainly not essential,
> as absolute frequency stability would not be of prime importance. Getting
> the phase noise as low as possible would be more important. I expect better
> performance can be achieved if one forgets about locking the signal source
> to something else, but I may be wrong.
> 
> An HP 8663A sig gen has <-147 dBc/Hz at 10 kHz offset, but I'd hope its
> possible to produce something better than is possible in a commercial sig
> gen that covers up to 2.5 GHz.
> 
> Dave
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.