Yaesu FT-1900R Operating Manual page 87

"S " M M
ET ENU ODE
M S D
ENU ELECTION ETAILS
59 W/N DV
Function: Reduction of the Microphone Gain/Deviation and receiver bandwidth.
Available Values: WIDE (±5 kHz Deviation, 15 kHz Bandwidth) / NARROW (±2.5 kHz
Deviation, 6 kHz Bandwidth)
Default: WIDE (±5 kHz Deviation, 15 kHz Bandwidth)
FT-1900R O M 83