[Elecraft] Re: AGC adjustment

Wed Apr 30 10:31:00 2003

Wayne...thanks much for explaining in more detail the adjustment and action 
of the K2 AGC....based on this I've landed mine at 3.75v and really like 
what I'm hearing now....tons of audio when needed, good S-meter sensitivity 
and kool AGC action!

This convinces me I'm not having any problems with the receiver and all is 
working great! Some of my replys about AGC action I posted hinted I had a 
receiver problem but hey....I knew better! Ya right....

By-the-way, I do retract my comments regarding the K2 having puny 
audio....now with AGC on at the new, improved setting I can still turn it up 
enough to blast me outa the shack and also to "mask" my wife's hollering at 
me to turn the DAMN THING DOWN!! ....what did you say dear?

It has been kinda fun getting my hands "dirty" tweaking on the K2...I can't 
image ever trying this on a $3000+ import rig?  E G A D S!!! May be this is 
what its all about!

Good job guys....73

ed

>From: Wayne Burdick <[email protected]>
>To: David Gropper <[email protected]>
>CC: [email protected], [email protected]
>Subject: [Elecraft] Re: AGC adjustment
>Date: Tue, 29 Apr 2003 20:18:36 -0700
>
>
>
>David Gropper wrote:
> >
> > Wayne, Earl,
> >
> > I would sure appreciate a short email explaining what to do!
>
>
>Hi Dave,
>
>In practice, the setting of the AGC threshold pot is a compromise. Setting 
>it to
>a higher voltage results in the AGC coming on sooner, i.e. with 
>lower-amplitude
>on-air signals. Setting it to lower voltages prevents the AGC from reducing 
>the
>audio output level of the K2.
>
>The 3.8 volt setting, which is the one recommended in the K2 manual 
>(revision E,
>page 46), is a good choice for most operators. As the manual explains, you 
>can
>optimize this setting later if desired.
>
>The approach I take is:
>
>1. With an antenna connected, switch to a "quiet" band (one with light
>atmospheric background noise, e.g. 15 m at night). Tune to a place with no
>incoming signal.
>
>2. Turn AGC OFF (using PRE/AGC + AGC as explained on page 97 of the 
>manual). If
>the background noise level increases dramatically with AGC off, the AGC
>threshold is probably set too aggressively. A lower voltage setting, as 
>measured
>at pin 5 of U2 on the Control board, might be more appropriate. I'd try 3.5 
>or
>3.6 V for starters. (Note: when adjusting the AGC threshold, disconnect the
>antenna. Otherwise incoming signals could make it harder to adjust.)
>
>3. After selecting a different threshold setting, test the AGC on strong 
>signals
>to make sure you haven't set the threshold voltage too low.
>
>4. Finally, adjust CAL S HI and CAL S LO as explained on page 46.
>
>73,
>Wayne
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