Rick Karlquist N6RK wrote:

Finally a reply =)
thanks,

I have built numerous VCO's that work as you describe.

No technical papers recommendations?

A tuned coaxial line is used and the feedback is controlled
by a capacitor. Making the capacitor small will allow harmonic
oscillation, making it small will allow fundamental.

That was an initial thought, that, given a flat-gain amp, like a MMIC,
the coupling capacitors reactance would determine what frequency maximum
power would be transfered. The reactance the amplifier I/O impedance
matched the line I/O impedance.

Since you can make say a 9th overtone crystal oscillator,
there is no reason why you can't make a 9th overtone transmission
line resonator oscillator.

I'm thinking I should try a binary weighted series-L shunt-C ladder
network, with varactors for the C. Could switch the varactors into
forward conduction to tune out the end of the line, raising the frequency.

Latest Microwave News describes a nonlinear ceramic (BaZrTiO) thin-film
voltage-tuned capacitor. I've read about articles that use common
ceramic caps as VCO's, even the capacitor-equivalent of magnetic
amplifiers. The advantage of thin films is you can fabricate
voltage-tuned filters, as well as individual caps.

Now if I could just fabricate my own, using basement PCB lithographic
techniques, or my microwave oven to plasma sputter the film.

--
Scott

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