[Elecraft] AGC Alignment

W3FPR - Don Wilhelm w3fpr at earthlink.net
Sat Apr 9 08:44:36 EDT 2005


Evert,

If RP6 is on the high side of its tolerance and/or R1 is on the low side
combined with a low 8R voltage, you may not be able to achive the 3.80 volt
level.  3.75 to 3.78 volts is probably OK for your initial adjustment.  I
fine-tune my setting later so there is no AGC action with internal receiver
noise and usually end up with a setting somewhere between 3.7 and 3.75
volts, although some particularly hot receivers must be set as low as 3.6
volts.

To assure no AGC action on internal noise, remove the antenna, seto the RF
gain fully CW and AF Gain up until noise can be heard - then toggle the AGC
off/on by pressing AGC and PRE/ATT buttons together.  Adjust the AGC
Threshold just below the point where no change in noise is observed.  Be
certain the set CAL S Lo and CAL S Hi after changing the AGC Threshold
setting.

73,
Don W3FPR

> -----Original Message-----
>
> 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?
>
>




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