[Elecraft] K2 antenna 2 no antenna observation

[Ron D'Eau Claire]

I certainly agree with Don. 

There are two effects that can enhance signals at low audio levels, often
dramatically. 

One effect is the response of human hearing. Hearing responds more the
differences in levels with low level sounds. As the sound volume increases,
we perceive less and less difference in levels. (Our vision is like that too
in how it responds to light levels.)

The other is the system AGC configuration. If you reduce the signals below
the AGC threshold, the level between the signal and noise (S/N ratio) will
increase, sometimes dramatically. That's exactly why some of us turn AGC off
and ride the RF gain control, relying on the K3's hard limiter function to
protect us from any huge signals appearing in the band pass. (That's why
Wayne included a hard limiter in the K3 under CONFIG:AF LIM. It's active any
time the AGC is turned off.) 

73,

Ron AC7AC

-----Original Message-----
  There is some leakage between ANT1 and ANT2 -- so you just switched in 
an attenuator of some unknown value.  I will wager you had the preamp on 
too.  Next time, you might want to try turning off the preamp to lower 
the noise, and possibly turning on the attenuator.  That way, you do not 
have to switch to "no antenna", and you can answer the station without 
changing antennas.

73,
Don W3FPR

On 6/5/2011 4:52 PM, W2bpi1 at aol.com wrote:
> I was working a weak station with QSB that was at about my S4 noise level.
> Happened to hit ant. 2 button. Now the noise is gone but I can hear the
> station  weak but now solid copy. Interesting indeed! 72  Geo/W2BPI
> ______________________________________________________________