Most of us are well aware of the really nice SSTRAN kit, but has anyone tried this:
http://www.vectronics.com/Product.php?productid=VEC-1290K
??
Looks like a nice little starter kit but not a PLL oscillator. Rather, this is a free running oscillator tuned by a variable capacitor. A jumper selects the range of frequency and the capacitor sets the desired frequency in that range.
Some of these little circuits can be fairly stable if quality components are used in the oscillator circuit. Otherwise the frequency will drift a bit with changes in temperature. Also, poor designs will allow drift with slight input voltage changes.
A good mod would be to substitute the tuning components with a fixed crystal if a single operating frequency can be used.
But it's no SSTRAN! It lacks the modulation capability and the RF output level is no great shakes either. I don't know how you gents feel about it, but I can't stand a free running oscillator any more. All of my Part 15's are typically operating within 1 - 2 Hz of dead on.