Yaesu FTDX9000D Operation Manual

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Contents

Page 24 FTDX9000D OPERATION MANUALNB SwitchPressing this button activates the (analog) IF NoiseBlanker, which may help reduce many different typesof man-made impulse noise (but not atmospherics).When the Noise Blanker is activated, the LED insidethe button will glow red. Adjustment of the NoiseBlanker level is accomplished via the NB knob, de-scribed in the previous section.VRF/μ-T SwitchThis button turns the main band (VFO-A) receiver’sVRF filter or μ-TUNE filter on and off. While acti-vated, the LED inside the button will glow red.VRF/μ-T/NTCH KnobsVRF/μ-T KnobThe inner VRF/μ-T knob tunes the passband of themain band (VFO-A) receiver's RF filter (18 MHz andhigher Amateur bands) or μ-TUNE filter (Narrow-bandwidth High-Q RF Filter) (14 MHz and lowerAmateur bands) for maximum receiver sensitivity (andout-of-band interference rejection). On the 18 MHzand higher Amateur bands, this knob provides adjust-ment of the VRF (Variable RF Filter) preselector cir-cuit.Advice It is possible to use the Menu to de-select the μ-Tune module, and utilize VRF instead, on bandswhere a μ-Tune module is installed. However, thesuperior selectivity of the μ-Tune circuit is pre-ferred for most applications. The μ-Tune circuitry automatically tracks your op-erating frequency, and adjustment of its center fre-quency is normally not required. However, if avery strong signal within several dizen kHz iscausing you problems, you may use the VRF/μ-T/NTCH knob to skew the tuning to one side ofthe other of your current frequency, to roll off thestrength of the interfering station. If you wish to reset the tuning of the VRF/μ-T/NTCH knob to its original (centered) setting, justpress and hold in the VRF/μ-T switch (# above)for two seconds. The μ-Tune circuit will not re-vert to its normal (automatically tuned) position,centered on your current frequency. There is a slight increase in receiver path insertionloss when the μ-Tune circuit is engaged. On thefrequencies where μ-Tune is used, this is seldom aproblem. If the slight signal loss presents a prob-lem, just turn the μ-Tune switch (# abvoe) Off. Rotation of the VRF/μ-T/NTCH knob to adjustthe μ-Tune circuit should be performed only tooptimize the signal or reduce interference. Theμ-Tune circuit tuning is surprisingly sharp. If youare adjusting VRF, however, the tuning is muchmore broad, and we believe that VRF adjustmentwill seldom be required. The relative position of the μ-Tune or VRF pass-band can be observed on the TFT display.NTCH KnobThe outer NTCH knob adjusts the center frequencyof the main band (VFO-A) IF notch filter. The NotchFilter is engaged via the NTCH switch, described inthe next section.FRONT P ANEL C ONTROLS