Shortened list of VFO rules:
1) Keep RF power output to a minimum. (Depend on subsequent stages to build it up--WA8MCQ)
2) Feedback to maintain oscillation should he minimized.
3) Shield the Ls and C's of the VFO tank components.
4) DC supply instability and ripple should he minimized.
5) Decouple DC coming into the oscillator carefully.
6) Lightly couple the oscillator to the buffer.
7) The huffer stage should have constantinput impedance.
8) The huffer stage should have low reverse gain.
9) The fT specification of the oscillator device should be at least 20 times the operating frequency.
10) There should he a means of stabilizing oscillator amplitude.
11) Use low-temperature coefficient, low loss caps such as NPO, silver-mica, polystyrene.
12) Use parallel caps where RF current is high.
13) Use good quality air variables: brass plates, double-end bearings.
14) Use a solid air-wound coil on a ceramic, glass or plastic form.
15) Use Q-dope on home-made coils.
16) For coils with slugs, use low-temperature coefficient iron-powder material.
17) Keep slug penetration into the coil to a minimum.
18) Inductors and capacitors in the VFO tank shouldn't encounter any airflow.
19) Keep stray inductance and capacitance low: short lead length, wide ground return path (big ground plane), no
double-sided PC board construction.
20) Reduce mechanical vibration: mount all critical components securely; wiring should be solid, heavy gauge wire.