Yaesu FT-991 Operating Manual

Also see for FT-991: Manual Manual Operating manual Reference book Instruction manual

Contents

Page 50FT-991 O PERA T I N G M A N U A LWidth (iF dSp bAndWidth) tuning (SSb/cW/rtty/dAtA ModeS)The IF WIDTH tuning system allows you to vary the width of the DSP IF passband, to reduce or eliminate interference.Moreover, the bandwidth may actually be expanded from its default setting, should you wish to enhance incoming sig-nal fidelity when interference on the band is low.1. Press the F(M-LIST) button to display the functionmenu list. Touch the [WIDTH] icon to activate thisfunction and cause the MULTI knob to function asthe WIDTH adjustment knob.MULTI KnobF(M-LIST) ButtonWIDTH indicatorWIDTH level indicator2. Rotate the MULTI knob counter-clockwise to narrowthe bandwidth and reduce interference.Referring to Figure “B”, you can see the defaultbandwidth of the SSB mode.By rotating the MULTI knob to the left, the band-width will narrow (see Figure “A”), while rota-tion of the MULTI knob to the right, will increasethe bandwidth as depicted in Figure “C”.The default bandwidths, and total bandwidth ad-justment range, will vary according to the operat-ing mode:SSB Mode: 1.8 kHz - 3.2 kHz (default: 2.4 kHz).CW Mode: 500 Hz - 3 kHz (default: 2.4 kHz)RTTY/DATA (LSB, USB) Modes: 500 Hz - 3kHz (default: 500 Hz)AM Mode: Fixed at 9 kHzFM/DATA-FM/C4FM Modes: Fixed at 16 kHzA B CIF BANDWIDTH IF BANDWIDTH IF BANDWIDTHMULTI MULTI MULTIA dvice : To increase the bandwidth, rotate the knob clock-wise. Rotate the MULTI knob to display the bandwidthof the IF filter below the [WIDTH] indicator (Re-fer to the instruction below). For reference, the level indicator on the TFT dis-play shows the bandwidth.interference reJection