AGC Settings 

  
AGC Settings for the Elecraft K3 are not at all critical.  But since so many have asked, below are my everyday AGC settings that work well for me in dx'ing, 
contesting and ragchewing.  The combination of these AGC settings and the Gain adjustment technique described below will favor those who like a quiet 
receiver with signals that "pop" decidedly out of the noise.  The K3 receiver can NEVER be considered noisy if setup properly in this manner.



Menu
Setting
AGC DCY
Soft
AGC HLD
0*
AGC PLS
Off
AGC SLP
15
AGC THR
5
AGC F
80
AGC S
20


*   it is worth experimenting with AGC HLD 0.3 to 0.5 for SSB rag chewing or contest pileups - I prefer to use AGC Off for contest pileups
   


Gain Adjustment

The Elecraft K3 and Ten-Tec Orion, with their hybrid analog/digital RF-IF chain, offer significantly more receiver gain than operators are used to.  Simplistically 
setting RF Gain to maximum, which worked with radios of yore, will yield unsatisfactorily noisy results in almost EVERY case.  Some degree of RF Gain 
"throttling" must be engaged by the user and is crucial to the proper operation of the K3 and Orion receivers and enjoyable listening.  Elsewhere, I've presented 
the excellent gain adjustment instructions prepared by K3NA and W4ZV.  I will present a simplified interpretation here:  

If at all possible, use headphones for listening.  The more isolation the headphones provide, the better.  Sennheiser HD-280 phones are highly recommended.
Determine the appropriate AF Gain (AFG) setting - once determined, this is the AFG setting you will normally use all the time:
turn ATT off, PRE on, and RF Gain (RFG) maximum
tune in a very strong (s9+) signal
adjust AFG to a moderately loud but comfortable level   (first set AF Gain Hi/Lo in the config menu - I recommend the LO setting for headphones)
note the position of the AFG control - this is your AFG setting - leave it at this level, all the time
With ATT off, PRE on, and RFG max - tune to an empty part of the band so you're just listening to band noise with the antenna connected
 
Assuming you have an antenna switch inline with your feedline, switch the antenna in and out - if you clearly hear an increase in band noise as you connect 
the antenna, repeat the test as you decrease gain in this order: 
turn PRE off
turn ATT on
decrease RF Gain control

You want the least amount of gain that still allows you to hear an increase in band noise when the antenna is switched in.

FYI, on 20M with a tribander, I typically have PRE off, ATT on, and RF Gain from 2 - 3 o'clock.  Even on 160M with a Beverage rcv antenna, I typically have 
PRE off always and ATT on half the time

(so for simpletons, just turn PRE off and ATT on and you'll be 90% of the way there, 90% of the time unless you have lossy antennas or very quiet bands)

Congratulations, you're done - your AF Gain and RF Gain settings are now optimized. Feel free to make slight adjustment to RF and AF Gain as desired.

The K3 will remember your PRE and ATT settings as you make these adjustments on each band and for each antenna input.