[Elecraft] Voltage reading on K2 display low

[Don Wilhelm]

Eddy,

I suggest you investigate with your DMM.
You could have a significant voltage drop at the power cable - if there 
are DC distribution boxes in the path they may be a problem, your 
connectors along the path may not be tight.

What you can do is investigate whether the internal voltmeter is telling 
you the same voltage that is being fed to it.  You have a switch on your 
control board that should be in the "INT" position - that is with the 
switch handle slid completely over to the left with the front of the K2 
facing you.  Measure the voltage between ground and the center pin of 
that switch and compare that reading with the voltage shown on the K2 
display.
If there is a significant difference (less than 5% difference is NOT 
significant), you can try slightly adjusting the values of R9 or R10 
depending on whether the reading is high or low.

The K2 display will always read lower than the power supply voltage 
because there is a small drop across D10 and also F1.  If you install 
the A to B mods, D10 is changed to a liode with a lower voltage drop.

73,
Don W3FPR

On 3/10/2012 2:49 PM, Eddy wrote:
> Checking the clock time on my K2 (about 10 years old now) I noticed the power supply voltage as displayed is 2 volts lower (E 11.8) than the actual power supply voltage which is set at 13.4 .....
>
> When I built my K2 many years ago I don't remember this being off by so much, so is this an indication of a problem inside the K2? It makes full power and every function seems to operate normally........
>