[Elecraft] VCO Alignment

[Don Wilhelm]

Jim,

The most common source of problems with the PLL or VCO is a solder bridge on
the thermistor board.  There are other possible sources, but check there
first.  You can often get to the back of the thermistor board by removing
the front panel and the control board.

You intermittent display is most likely an unsoldered connection (or poorly
soldered) - usually on the front panel itself.

So check the soldering first, then re-check the soldering, and when that is
done, check the soldering - that is the most common failure and misplaced
components runs in second place.  Bad components are way down the list.

73,
Don W3FPR


> -----Original Message-----
>
> I am building K2 #5731 and I have run into two problems.  The
> first, and most serious, is in VCO alignment.  When moving L30,
> the voltage at the left end of R30 does not change from 8.03vdc.
> I have been through the entire range of L30, very carefully, with
> no change.  I pulled out T5 and rewound it.  It is as nearly
> perfect as I can get it.  When I measure vdc on T5, I see
> approximately 0.01vdc on 1 and 2 and 2.65 on 3 and 4.  I checked
> voltages on U4 and U6 and they are in the range of the table in
> the back of the manual.  I've checked all the components
> installed and the soldering.  This is my second K2 and I have
> been a lot more careful.  I'm stumped.  Anybody got any ideas.
>
> The second thing is that parts of the mode indicator on the
> display have become intermittent.  Any ideas on that?
>
> Thanks.
>
> Jim, K4ZMV
>