[Elecraft] AGC Alignment

[Paul Bruneau]

At least a few of us saw exactly the same thing in the last few weeks. 
We never heard anyone giving grave warnings that we were in 
trouble...so I don't know what to tell you, except that I'm in exactly 
the same boat.

I planned on measuring it again when I get to the next alignment/test 
where that board is powered up. For now I'm still winding toroids.

-Paul KB8NMZ
K2 #4818

On Apr 9, 2005, at 7:38 AM, Evert Bakker wrote:

> Hi all,
>
> I'm assembling the K2 here (SN 4836) and came to the first 
> check/alignment.  No smoke here so far, but when adjusting the setting 
> for the AGC as described on page 47 I became suspicious about the 
> alignment procedure. Adjust R1 for 3.80 V on the DMM. I turned R1 and 
> reached the end and got stuck on 3.78V. The absolute value of 3.78 
> doesn't worry me but that I ended up at the limit of the R1. I thought 
> I should check all variables like DC voltage which should be 8V (was 
> 7.98V so OK). Checked the resistors (mainly RP6 / 5.1K) and, RF gain 
> potentiometer 5K and the R1 (50K). All looked fine. So what's wrong?
>
> I started making calculation on the resistor dividing network and came 
> to the conclusion that the maximum voltage (theoretically) could be 
> close to 3.82V when the RF-gain is fully CW  (0 Ohm) and  the R1 is 
> set fully CCW (50K).
>
> I wonder if something is wrong here and if not, why was the alignement 
> procerdure setup like this (it could heve been something like: Set 
> RF-Gain full CW, R1 full CCW and check the voltage at pin 5 of U2 to 
> be close to3.80V)? Or did I miss some errata info?