Icom IC-7300 Instruction Manual basic - Page 33

4 RECEIVING AND TRANSMITTING Using the Twin PBT SSB, CW, RTTY and AM modes In general, the Twin PBT (Passband Tuning) electronically narrows the IF passband width by shifting the IF frequency to slightly outside of the IF filter passband, to reject interference. The IC-7300 uses DSP for the PBT function. You can narrow the IF passband width by rotating both TWIN PBT CLR inner (PBT1) and outer (PBT2) to the opposite direction from each other. LYou can see the nearby signal using the Spectrum Scope (Section 5). 1. Rotate TWIN PBT CLR inner (PBT1) and outer (PBT2) to the opposite direction from each other. LLInformatio ••Match both the TWIN PBT CLR (inner) (PBT1) and outer (PBT2) filters before operating the Twin PBT. ••Rejects interference of both higher and lower passbands. ••If you rotate the control too much, the received audio may not be heard because the passband width is too narrow. ••Displays the passband width and shift value. ••A dot is displayed above the passband width when you rotate TWIN PBT CLR . ••Hold down TWIN PBT CLR for 1 second to clear the PBT setting (the dot disappears). ••The PBT is adjustable in 50 Hz steps in the SSB, CW, and RTTY modes, and 200 Hz in the AM mode. In this case, the center shift value changes in 25 Hz steps in the SSB, CW, and RTTY modes, and 100 Hz in the AM mode. ••Rotating both the inner and outer controls to the same position shifts the IF left or right. PBT is OFF PBT2 PBT1 Cutting lower passband PBT2 PBT1 1 2 3 4 5 6 2. Touch the Filter icon for 1 second to display the current passband width and shift frequency. 7 ••Opens the FILTER screen. Passband Shift 8 width value 9 10 FILTER (SSB) screen (while operating Twin PBT) 11 IF center frequency Passband center frequency 12 SFT: Shift value 13 PBT1 PBT2 BW: Passband width 3. To close the FILTER screen, push EXIT . NOTE: While rotating TWIN PBT CLR , you may hear noise. This comes from the DSP unit and does not indicate an equipment malfunction. 14 15 16 17 18 19 Cutting both higher and lower passbands 20 21 PBT2 PBT1 Passband Passband IF center frequency Interference Desired signal 4-3 Interference Desired Interference signal