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

[jimlux]

On 5/30/16 4:06 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 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.


Multiply up from a clean source.
A $200 Wenzel streamline OCXO is -130 at 10 Hz, -155 at 100 Hz and -165 
from 1 kHz out.

20logN is 21 dB, so you should be able to get -140 or better at 116MHz, 
if you're careful.

A Wenzel ULN is about 10 dB quieter..
The 10 MHz ULN is about -175 dBc/Hz from 1kHz on out.

You can get a ULN for VHF (it won't be cheap) but they quote -175 dBc/Hz 
at 10kHz out for 100 MHz oscillators.

The 8663 -145 at 10 kHz spec is for the rear panel 640 MHz output, I 
believe.
On the front panel, from 0.01 to 119.9, with the H40 option, the spec is 
-132 dBc, (-142 from 120-160 MHz)

Of course, you'd have to find a working 8663A (and keep it working).
The E8663B isn't as quiet (and is also obsolete).
The E8663D at 100 MHz is -150 dBc/Hz at 10 kHz out.


> Dave
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