[Elecraft] FT8 Transmit Problem

[Terry Hines]

I'm having trouble with the I/F between Windows 10 and the USB sound card in
my upgraded K3. I've checked and the Sound Card settings in Windows 10 and
they are exactly as shown in Chapter 10 of Fred Cady's book. It receives and
decodes FT8 perfectly but can't transmit. When I hit the "Tune" button on
the WSJT-X screen the red "PTT" light comes on but there is no input signal
to the K3 and hence no RF output. What am I doing wrong?

Terry N4ZH