[Elecraft] AGC Modification to the K2

[Darrell Bellerive]

Dave,

I have just read through your modification and I really like what you have 
designed.

I have never been able to get my AGC set to where I felt it should be. 
Regardless of where the AGC threshold trimmer (R1) is set, there is always 
more receiver gain with the AGC off. And moving the AGC voltage down from the 
recommended 3.8 volt setting reduces the range of the RF gain control.

Have you measured the overall receiver gain increase with this mod?

It would also be interesting to see Jack Smith, K8ZOA's AGC analysis on a 
modified K2.

I am anxious to try this mod.

Darrell


On February 24, 2007 08:04 am, Dave White wrote:
> I have created a small modification to the AGC circuit of the Elecraft K2.
> It alters the AGC onset point of the MC 1350 IF Amplifier (U12), which
> results in more gain at the IF stage, and subsequently more audio output.
> The mod involves replacing RP 6 and R1 with a series of three
> commonly-available potentiometers and adjusting the pots so that the RF
> Gain control swings the AGC line voltage through new values.
>
> I've authored a short 3-page article that describes the modification. I'll
> send it to anyone who replies directly to me at dwds at trinustech.com. There
> is NO parts kit, so please don't ask. If there is enough interest, I'll
> submit it to Eric or Wayne at Elecraft to see if they want to post it on
> the website.
>
> THE USUAL DISCLAIMER APPLIES: This is NOT an authorized Elecraft
> modification and you implement it at your own risk.  It worked for me, but
> may not for you.
>
> Regards
>
> Dave White
> VE6DRW
> dwds at trinustech.com
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

-- 
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada