Icom IC-7700 Instruction Manual - Page 66

4 RECEIVE AND TRANSMIT D Convenient functions for receive • Preamp (p. 5-9) ➥ Push [P.AMP] (MF3) several times to set the pre- amp OFF, preamp 1 ON or preamp 2 ON. • Push and hold [P.AMP] (MF3) for 1 sec. to turn the preamp function OFF. • "P.AMP1" or "P.AMP2" appears when the preamp 1 or preamp 2 is ON. • Attenuator (p. 5-9) ➥ Push [ATT] (MF4) several times to set the attenu- ator in 6 dB steps. • Push and hold [ATT] (MF4) for 1 sec. to turn the atten- uator function OFF. • "ATT" and attenuation level appear when the attenu- ator is ON. • Noise blanker (p. 5-16) ➥ Push NB to turn the noise blanker ON and OFF, and then rotate [NB] control to adjust the threshold level. • Noise blanker indicator (above NB switch) lights when the noise blanker is ON. • Push and hold NB for 1 sec. to enter noise blanker set mode. • Twin PBT (passband tuning) (p. 5-12) ➥ Rotate [TWIN PBT] controls (inner/outer). • PBT indicator (above PBT-CLR switch) lights when PBT is in use. • Push and hold PBT-CLR for 1 sec. to clear the settings. • Noise reduction (p. 5-17) ➥ Push NR to turn the noise reduction ON and OFF. • Rotate [NR] control to adjust the noise reduction level. • Noise reduction indicator (above NR switch) lights when the noise reduction is ON. • Manual notch filter (p. 5-18) ➥ Push NOTCH to turn the manual notch function ON and OFF. • Rotate [NOTCH] control to set the attenuating fre- quency. • Notch indicator (above NOTCH switch) lights when the manual notch is ON. • AGC (auto gain control) (p. 5-11) ➥ Push [AGC] switch several times to select AGC FAST, AGC MID or AGC SLOW. ➥ Push AGC VR to turn the AGC time constant manual setting ON and OFF. • Rotate [AGC] control to adjust the time constant. • 1⁄4 function (p. 3-6) ➥ Push [1/4] to turn the 1⁄4 function ON and OFF. D About RTTY reverse mode Normal Reverse 170 Hz 2125 Hz 2125 Hz 170 Hz Space Mark BFO BFO Space Mark Received characters are occasionally garbled when the received signal has Mark and Space tones reversed. This reversal can be caused by incorrect TNC connections, setting, commands, etc. To receive reversed RTTY signals correctly, select RTTY-R mode. ➥ During RTTY mode, push and hold RTTY/PSK for 1 sec. to select RTTY and RTTY-R mode. D Twin peak filter APF/TPF The twin peak filter changes audio frequency response by boosting the mark and space frequencies (2125 and 2295 Hz) for better reception of RTTY signals. ➥ During RTTY mode, push APF/TPF to turn the twin peak filter ON and OFF. • " TPF " appears in the LCD and the [APF/TPF] indicator above this switch lights green while the filter is in use. NOTE: When the twin peak filter is in use, the received audio output may increase. This is a normal, not a malfunction. 4-14