[Elecraft] Low receiver sensitivity

[Bill Coleman]

On May 10, 2005, at 10:36 AM, info4mjs at att.net wrote:

> I recently assembled and XG1 calibrator and began checking some of  
> my equipment.  4 out of 5 radios that I own indicated an S9 signal,  
> however, my K2 did not.  It registered an S5-S6.  A friend of mine  
> who borrowed my K2 indicated the receiver seemed to be a bit weak.

Is the receiver provably weak, or is the S-meter just stingy? The K2  
receiver may be working just fine, you're S-meter may just be  
adjusted so that it is very stingy.

I had troubles with my AGC and S-meter on my K2. My notes are in the  
archives.
<http://www.ac6rm.net/mailarchive/html/elecraft-list/2002-03/ 
msg00740.html>

I eventually figured this out. I changed R1 to 30.1 k (newer K2s are  
adjustable here) and picked D1 to be a diode with a higher Vf. These  
measures helped a little, after I re-adjusted S-HI and S-LO.

The real problem was that Q12 was bad. Since I didn't have a PN2222A,  
I substituted a 2N2222A (metal TO-18 package). It's been working  
great for a couple of years now.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901