It's kind of an interesting device. Essentially, the resistor sets a voltage that then is used to control an internal
master oscillator, voltage controlled. There is a programmable divide by (1, 10 or 100) to range the output. The result
is 1khz to 33mHz operation.
I was really surprised by the immunity of the device to outside forces, such as load resistance/capacitance changes,
power supply variations and even physically touching the IC while operating. Stability is good in that respect. Of course,
the issue is the phase noise caused by the dividers, etc. There's quite a bit going on in that IC ! You can readily hear
the frequency compensating and locking circuitry working - step-changing the frequency slightly, when listening to the
output in a local receiver with the BFO turned on.
I didn't make lots of quantitative measurements, but I did do a simulation by mixing the oscillator output with the antenna input
to a receiver, listening around. Tuned dead-on, it's beautiful - tune off frequency, and you're slope-detecting the phase
noise and this shows up as low level hiss. I set the oscillator 10kHz away from an existing AM QSO. The hiss generated by the
60 over S-9 oscillator 10Khz away was noticable in the background of the 20 over S-9 QSO.
The hiss reminded me of some of the very early synth VFOs that I heard on the air during the '70s. I believe Roger, K1CZH had one, and he
had a very noticable hiss on his signal.
This little oscillator is too hissy for a VFO except maybe for a PW rig, but for 2 bucks, I am reasonably impressed by the performance and stability.
And, it was a good test for working with surface mount
Talk later and Regards,
Steve (clip lead alley!)
