[Elecraft] [K2] Lost 80m recieve.

[Don Wilhelm]

Al,

Just to add a little to the "sensibility" of the VCO (R30) voltage readings:
The range of voltages possible is from 0 to about 8 volts.  Your high 
voltage readings indicate that the PLL is trying to increase the voltage 
to the varactors in order to reduce the capacity - and the op amp has 
simply "run out of steam" and can go no higher.  Voltages between 1.5 
and 7 volts are workable, but outside that range, the varactors are not 
linear.

A higher than normal voltage means there is excess capacity in the VFO 
range select controls, and a low voltage means that there is not enough 
capacity in the circuit.
Relays K13, K14, and K15 control which fixed capacitors are placed in 
the circuit, and are in parallel with varactors D23 through D26.

On 9/6/2011 9:03 AM, Alan Davenport wrote:
> I just performed the VCO voltage checks you asked for and here are the results. It looks like it was worse than I thought. 40,30,20 and 12 meteres are all within spec. The other bands are as follows:
>   
> 3.5 MHz = no output
> 4.0 MHz = no output
> 18.0 = 7.94v
> 18.2 = 7.94v
> 21.0, 21.45, 28.0 and 28.8 are all also fixed at 7.94V.
>   
> I never noticed the other bands had gone dead as I operate mostly on 40m CW some operation on 20m and 30m.  "When are the higher bands ever going to open up?" hihi
>
>