Check out this circuit:

http://www.edn.com/archives/1998/111...s/23DI2294.pdf

It will easily tune an octave with just a few volts of tuning voltage.

Joe
W3JDR


"James Bond" wrote in message
...
i'm after a circuit for a 2m VCO.

basically i'm planning to homebrew a kind of tracking generator, where I
can sweep across 2m to look at filter shapes, etc.


my plan is to sweep, using a vco, across 2m using a sawtooth waveform.
this waveform will also be amplified and fed to an oscilliscope, to give
me a horizontal sweep.

the output from the filter will then be fed to a RF millivoltmeter circuit
(again, anyone got any good circuits?) and this will then be fed into a
logarithmic converter then be put onto the Y deflection, to give me
amplitude.


calibration will be by putting the system into "manual" mode and
connecting to a frequency counter, then sweeping up and down until get
specific frequency, then the x-centering be used to set this on a known
point.



basically anything that having say 1-6V in giving a 140 to 150mhz sweep
would be grand, then i can play with amplifiers to get it just as i want.


thanks all!

dr. x