[Elecraft] Sub Band Speakers on 15M Band

[KD3TB]

With the K3 in Split mode and Sub turned on, on 20 Meters I can hear the
Main and sub band in separate headset speakers, but cannot  on 15 Meters

 

Is there a Config/Menu function that has to be set by band?

 

Thanks, 

 

Irwin  - KD3TB