Many inexperienced users complain about the Elecraft K3 and Ten-Tec Orion receivers as being "noisy". Unfortunately, to get the amazing performance that these receivers are
capable of, you can't take the simplistic approach of maximizing RF Gain with preamp engaged thinking that's the way to hear weak signals. It just won't work with these radios.
Following is an edited version of the instructions for K3 receiver gain adjustment posted to the Elecraft reflector by Bill W4ZV
Note: Please also look at the simplified version of these instructions contained in my AGC/Gain Settings page
Note that K3NA's original setup is for AGC Off, which is probably not a good idea for most casual users.
1. Have available your desired antenna and a dummy load (both on a coax switch is ideal) for each band you want to set up (you'll at least need to do this for major segments like 80/160, 40-18, 15-10 and 6 separately (if you have the external preamp).
2. Set AF GAIN back to about 9 o'clock and RF GAIN to MAX (fully clockwise). This assumes you have the proper AF GAIN menu setting for your specific headphones ( I use AF GAIN - LO for my 32 ohm headphones and still have tons of audio).
3. In the following order (first ATT ON, then ATT OFF, then PRE ON) alternately switch between your antenna and the dummy load. When you hear noise increase when switching to the antenna, use the lowest gain setting (i.e. ATT will likely be the correct setting on the noisy low bands and PRE will likely be correct for 10m). Remember that the K3 will remember these settings for each band. Once you have the correct setup on each band it will automatically recall that PRE/ATT setting when you return to that band.
4. Now adjust the RF GAIN knob counterclockwise until the antenna noise on the meter just stops flickering on the meter. This will be familiar to OTs since this is the way we set RF GAIN many years ago on analog radios.
5. Now adjust your AF GAIN knob for a comfortable listening level (mine is normally 9-10 o'clock which may vary depending on what type of headphones you have).
Regarding settings for speakers, I never use them since I'm normally listening for extremely weak signals on 160m or in contests and I don't want ANY extraneous noise between my ears and the signals. Perhaps someone who uses speakers can add comments.
My general rule for all gain settings (PRE/OFF/ATT, RF Gain knob, AF Gain knob, CONFIG: AF GAIN) is LESS IS BETTER (as long as you can hear signals). This is contrary to the thinking of some but following it will ensure that you get the ultimate dynamic range performance available from the K3.
73, Bill W4ZV