Yaesu FT-2000 Operating Manual

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Page 57FT-2000D OPERATING MANUALWIDTH (IF DSP B ANDWIDTH) T UNING (SSB/CW/RTTY/PKT MODES)The IF Width tuning system allows you to vary the width of the DSP IF passband, so as to eliminate interference. Moreover,the bandwidth may actually be expanded from its default setting, should you wish to enhance incoming signal fidelity wheninterference on the band is low.INTERFERENCE REJECTION (SIGNALS WITHIN 3 KHZ)Rotate the [WIDTH] knob to adjust the bandwidth.Counter-clockwise rotation reduces the bandwidth, whileclockwise rotation increases the bandwidth.ADVICE: The IF Width affects the Main band (VFO-A) only. The bandwidth of the IF can be observed on the dis-play.CAUTION:When rotating the [WIDTH] control fully counter-clock-wise, the transition between 50 Hz and 25 Hz bandwidthmay be accompanied by a “ping” sound, depending on theamount of noise present. This is a normal condition, andyou should turn down the volume, when wearing head-phones, to minimize the amplitude of this momentarysound.Referring to Figure B, you can see the default band-width with the [WIDTH] knob set to the 12 o’clockposition.By rotating the [WIDTH] knob to the left, the band-width will narrow (see Figure “A”), while rotationof the [WIDTH] knob to the right, as depicted inFigure “C,” will widen the bandwidth.The default bandwidths, and total bandwidth ad-justment range, will vary according to the operat-ing mode:SSB Mode: 200 Hz ~ 4.0 kHz (2.4 kHz)CW Mode: 25 Hz ~ 2.4 kHz (2.4 kHz)RTTY/PKT Modes: 25 Hz ~ 2.4 kHz (500 Hz): bandwidth at 12 o’clock position of [WIDTH] knob.[WIDTH] KnobWIDTH IndicatorIFBANDWIDTHIFBANDWIDTHIFBANDWIDTHUsing IF Shift and Width TogetherThe IF Shift and Variable IF Width features togetherform a very effective interference-fighting filter-ing system.For example, in Figure “A” you can see how inter-ference has appeared both on the high and low sidesof the desired signal. By rotating the [WIDTH]knob, as shown in Figure “B,” the interference fromone side can be eliminated, and by re-positioningthe [SHIFT] knob (Figure “C”), the interferenceon the opposite side can be removed, without re-introducing the interference previously eliminatedin Figure “B.”Advice: For best interference reduction, the Widthand Shift features are the primary tools you shoulduse. After narrowing the bandwidth (Width) and/oradjusting the center of the passband (Shift), theContour control may also yield additional signal-enhancement benefits on the net residual bandwidth.What’s more, the IF Notch Filter (see the next sec-tion) may also be utilized, in conjunection with thethree other filter systems, to significant advantage.A B CIFBANDWIDTHIFBANDWIDTHIFBANDWIDTHDesired Signal Desired Signal Desired SignalQRMQRMQRMQRMQRMQRMA B C