The Elecraft K3 is controlled using it’s rs-232 port and sound is ported IN through the rear mic jack and OUT through the line out jack.
A rs232 serial to usb adapter will need to be used to connect the K3 to any one of the usb ports on the RPi.
Sound: (Using a USB sound card: USB Sound on Amazon)
(KIO3 Mic In/Line Out):
a) Connect the RPi usb sound mic jack to K3 Line Out.
b) Connect the RPi usb sound headphones jack to K3 rear mic/mono.
c) Set K3 Config:LIN OUT:press#1 value to 20 (this can be adjusted later to personal preference.)
d) Set K3 Config:LIN OUT:press#2 value to 0
e) Set K3 Menu:MIC SEL to rP.L (make sure bias is off (#2))
a) Set K3 Config:AUTOINF to nor.
b) Set K3 Config:PTT-KEY to OFF-OFF.
c) Set K3 Config:RS232 to 38400.
- Turn the Monitor level to zero to eliminate echo when you transmit.
a) RemoteTX Audio Tab: Set TX Mod/RX Level settings to 20 each. Also, make sure AGC is unchecked.
b) RemoteTx Radio Tab: Set Mic-Gain to 30.
c) RemoteTx Radio Tab: Set TX CMP to 20.
Connect Power Control Relay pins to Pin 5 and Pin 8 on the RS-232 of the K3.
See Power Control Relay Details: