[Elecraft] How varactors work

[Ron D'Eau Claire]

Recently I asked about the recommendation to reduce the size of the
resistor in the circuit between the DAC and the varicaps used in the PLL
Reference Oscillator. Wayne explained that they rectify some of the r-f,
producing a d-c bias as a result. With the 10k value the circuit
originally used, the DAC couldn't pull the tuning voltage down much
below 0.5 vdc. 

From that I'd conclude that those varicaps make pretty good rectifiers
at the frequencies used in the K2 oscillators.

Ron AC7AC
K2 #1289