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

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.

Rick N6RK

"Scott Stephens" wrote in message
news:tnamc.36397$0H1.3120575@attbi_s54...
If I have a waveguide, coax, or even lumped varactor tuned LC tank,
could I simply select which harmonic I want it to oscillate at, by
tunning a negative resistance?

Perhaps with the use of a "register key", such as is on flutes and
clarinets? I suppose that functions as a high-pass filter on the line,
when the hole is unplugged.

I'm interested in a multi-decade VCO, tuned with one control voltage and
just a few switches.

No, I don't want to heterodyne or synthesize, because I'm interested in
the regenerative/super-regenerative capabilities.

Any applicable app notes or articles? Dream on?

--
Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************