[Elecraft] K3 Transmit thru Line-In

[Bud Governale, W3LL]

I can't get any transmit audio via the Line-In connector.

Connecting the Mic cable to the rear panel MIC connection produces good transmit power and audio.

I know audio is coming from the sound card output because it also drives the computer speaker via its line in 
connection.

I tried moving the Mic connector from the rear panel MIC to the Line-In rear panel position. This still would not 
produce K3 SSB output.

Moving the Line-In connector to the MIC rear panel connector produces good transmit power and audio.

The TX lights each time but no output via Line-In
The K3 is in LSB mode.
TX TEST is in normal.
MIC SEL is RPH
MIC + LIN is ON.
MIC Gain is 30
Comp is 22.

Why can't I transmit thru the Line-In connection?

73,

Bud W3LL
w3ll at arrl.net