[Elecraft] K2 7747 VCO alignment problem

[Don Wilhelm]

Keith,

Not a nice problem to address.  I can give you some troubleshooting 
information if you are willing to hang in there with me.
Eliminate the "[Elecraft]" from the subject line and reply to me 
directly (not to the list).

Relay K15 is common on all those bands, but not on 80 and 40m, but that 
does not explain why 15 meters is OK.
Check the resistance between pins 1 and 10 of all 3 relays - that is the 
coil resistance, and if I recall, it is about 235 ohms.

Check that C73 and C74 are the correct values.

If that does not reveal the problem, you will have to measure the 
open/closed state of the relays for the next step.  Can you find those 
relays on the schematic?  They are all shown in the reset state.

73,
Don W3FPR

On 7/13/2020 2:52 PM, Keith Hamilton wrote:
> I am having trouble with the K2 VCO alignment. I have moved the T5 windings
> and obtained 6 volts at the left end of R30. I then went on to the chart
> (table 6-1) to measure the voltages at the listed frequencies. My readings
> are ok on 80 40 and 15 meters (between 1.5 to 7.5 volts) but on 30,20,17
> ,12 and 10 meters the voltage is 8.29 volts and does not change.
> 
> I have checked the solder connections of T5 and the value of C72 (271). The
> diodes D21,D22,D23, D24, D25 and D26 are correctly installed. I also went
> over the solder connections of K13, K14 and K15.
>