IC-R8600 Filters: IF Filter, Twin PBT, Notch, Noise Blanker & Noise Reduction

Summary: How to shape reception on the IC-R8600: the digital IF filters, Twin PBT, notch filters, noise blanker, noise reduction, AFC and CW settings.

Digital IF Filters

Each mode has three digital IF filters. Touch the filter icon to cycle FIL1 (wide), FIL2 (mid), FIL3 (narrow). To adjust the width touch the icon for 1 second, touch BW and rotate the MAIN DIAL (not possible in FM, WFM or DIGITAL). Changing the width resets the Twin PBT to centre. In SSB and CW you can choose the filter shape, SHARP (steep, almost ideal shape factor and better audio) or SOFT (rounded like an analogue filter, lower noise and better for very weak signals).

Default filters and adjustable ranges:

• SSB: 3.0, 2.4, 1.8 kHz (50 Hz steps to 500 Hz, then 100 Hz steps to 3.6 kHz)
• CW: 1.2 kHz, 500 Hz, 250 Hz (same range)
• FSK: 2.4 kHz, 500 Hz, 250 Hz (50 Hz to 500 Hz, 100 Hz steps to 2.7 kHz)
• AM/S-AM: 9.0, 6.0, 3.0 kHz (200 Hz to 10 kHz in 200 Hz steps)
• FM: 50, 15, 7.0 kHz (fixed); WFM: 200 kHz (fixed)
• D-STAR, P25, NXDN-n: 15, 10, 7.0 kHz; dPMR, NXDN-vn, DCR: 10, 7.0, 5.0 kHz (fixed)

Digital Twin PBT

SSB, CW, FSK and AM. Twin PBT (passband tuning) narrows the IF passband by overlapping two filters (PBT1 and PBT2) to reject interference. Push the multi-dial, touch PBT1 or PBT2 and rotate: rotating them in opposite directions narrows the passband, and moving both together shifts it. It adjusts in 50 Hz steps (SSB, CW, FSK) or 200 Hz (AM). Touch PBT1 or PBT2 for 1 second to clear. Noise while adjusting comes from the DSP and isn’t a fault.

Notch Filter

Touch NOTCH to cycle AN (Auto Notch, which attenuates beat tones automatically; SSB, AM and FM), MN (Manual Notch; SSB, CW, FSK and AM) and OFF. In CW or FSK only MN is available; in FM or DIGITAL only AN. Touch NOTCH for 1 second to set the position and the width (WIDE, MID or NAR).

Noise Blanker (NB)

SSB, CW, FSK and AM. Removes pulse noise such as car ignition. Touch NB; touch it for 1 second to adjust LEVEL (0-100%, default 50), DEPTH (1-10, default 8) and WIDTH (1-100, default 50). If strong signals distort or the noise isn’t pulse-type, turn it off or reduce the depth.

Noise Reduction (NR)

Digitally reduces random noise (effective in SSB, AM and CW). Touch NR; touch it for 1 second to set the level 0-15. Set it where the noise is reduced without distorting the signal.

AFC

FM, WFM and DIGITAL. Push the multi-dial and touch AFC to tune the receive frequency to the incoming signal (works regardless of the squelch). AFC Limit (Set, Function, default ON) limits the shift: for example +/-5 kHz for a 7 kHz FM filter, +/-10 kHz for 15 kHz, +/-25 kHz for 50 kHz and +/-100 kHz for WFM.

CW

• CW pitch: multi-dial, CW PITCH, 300-900 Hz (also the side tone) without changing the frequency.
• CW-R (reverse) reverses the BFO to avoid interference near the desired signal. The CW carrier side is LSB by default (SET, Function, CW Normal Side).
• SSB/CW Synchronous Tuning (default OFF) shifts the displayed frequency to keep the same signal when you switch between SSB and CW.

Duplex

Touch DUP on the FUNCTION screen to cycle DUP-, DUP+ and OFF; touch it for 1 second to set the offset (0.000-200.000 MHz in 1 kHz steps) and direction. Hold DIAL B (Monitor) to shift the receive frequency by the offset so you can hear the input side of a repeater. DUP blinks if the shifted frequency is out of range. Offset and direction are stored in each memory channel.