D L 4 X A V - jo 43 xn - h a m b u r g

+ + + - D L 4 X A V - jo 43 xn - h a m b u r g , g e r m a n y , e u r o p e , e a r t h + + +

Here the VFO tips that i have collected

To suppress noise from the voltage source and 78L08 (or similar), a lowpass is build with
R1 and huge C1 at the regulator output. this can increase the noise figure dramaticly
Everyone should know that C2 and C3 are needed against wild oscillation of
the voltage regulator (78xxx and 79xxx).
The two 100 nF condensers must be placed very close to the regulator to give good effect.

Frequency stability is the most importend thing for good operation.
G4JG (ex DL4CB) made a good VFO design published in CQDL 12.2004
Adjust P1 for lowest possible current and stable oscillation start at the band ends.

C1 and C3 should be as small as possible. C2 determines feedback coupling.
all other parts are not critical, except tuning coil and C, were only best components should be used.

home rig sat ant qsl info feedback links homebrew H F V / UHF disclaimer

dl4xav 2007