Ok Tom, just the second solution wants more job but creed also I that I am
the better .
Thanks still for the good suggestions.

73's de IK6GQC Rocco




"K7ITM" ha scritto nel messaggio
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Hi Rocco,

The specified phase noise seems respectable to me. The ones I've been
looking at have some very nice characteristics that I need, but phase
noise about -115dBc/Hz at 1kHz offset.

Though it might look like more work, I would use (2). If I used (1),
I would have a buffer amplifier from the oscillator, driving something
to generate rich harmonics...since you need an even harmonic, use an
assymetrical harmonic generator. Square waves, for example, have
extremely low even-order harmonics ("theoretically" zero). But with
(2), you can use a square wave to get the 3rd harmonic, and not have to
filter much 2nd or 4th, since there is little of either of those in
your square wave. A relatively simple filter at 120MHz will suffice.
Then the 480MHz helical must attenuate only signals 120MHz away, not
signals 40MHz away like in (1).

At least, that is my take on it. There are tradeoffs, always, and
therefore you will see different designs to accomplish the same thing,
and all will work.

Cheers,
Tom