User manual ICOM IC-761

[. . . ] AVOID placing the transceiver against walls or putting anything on top of the transceiver. During mobile operation, DO NOT operate the transceiver without running the vehicle's engine. When transceiver power is ON and your vehicle's engine is OFF, the vehicle's battery will soon become exhausted. This will avoid possible damage to the transceiver by ignition voltage spikes. [. . . ] · When operating in SSB mode, adjust output power so that the ALC reading in the ALC meter stays in the ALC zone. [RF PWR] NOTE: When connecting a TNC to the ACC socket on the back of the transceiver, rotate [MIC GAIN] fully counterclockwise and disconnect the microphone from the [MIC] jack. Transmit your AFSK signals using your computer's keyboard. FREQUENCY INDICATION DURING AFSK When operating AFSK in SSB mode, the indicated frequency is the signals carrier point. [EXAMPLE]: VHF band, FM mode, 1200/2200 Hz tone [EXAMPLE]: HF band, LSB mode, 2125/2325 Hz tone 2325 Hz 200 Hz 2125 Hz 1000 Hz Carrier point 2200 Hz 1200 Hz 36 FUNCTIONS FOR RECEIVE 5-1 Simple band scope SCP STEP 0. 5k 5 The band scope function allows you to visually check signal condition around a specified frequency. The IC746's band scope function can be used not only in FM mode but also when operating on HF bands. Sweep indicator Band scope indicator Frequency indicator mark Sweep step indicator INDICATOR SWEEP DESCRIPTION While the band scope is "sweeping, " " " appears; while stopped " " appears. Received audio is not emitted from the speaker while the band scope is "sweeping. " Indicates the relative strength of signals and their location in relation to the center frequency. Signal strength is relative to the S-meter level, S1 to S9, with each vertical dot in the band scope indicator equal to one segment of the S-meter. Signal activity is measured ±30 steps from the center frequency with each step equal to the selected sweep step. After a sweep, indicates the relative position of the selected frequency. When the selected frequency is outside of the sweep range, this indicator flashes. After changing the frequency, push [F3] to automatically return to the center frequency. equal to the selected sweep step. BAND SCOPE INDICATOR FREQUENCY INDICATOR MARK SWEEP STEP 1 ANT USB The band scope measures receive signal conditions over a specified range on either side of a selected frequency in either VFO or memory modes. While menu set 1 is displayed, push [F5](SCP) to S Po ALC SWR 1 3 20 5 7 9 50 20 40 60 100% BLANK select the band scope menu. CH VFOA 1 1. 5 2 3 Rotate the tuning dial to select a frequency. Push [F5](STEP) one or more times to select a sweep step. · During sweep operation " " appears and received signals cannot be heard. This function is only available in SSB, AM and FM modes. Push a mode key to select SSB, AM or FM mode. Push [APF/ANF] to toggle the auto notch filter ON and OFF. · "ANF" appears when the function is ON. [APF/ANF] 5-9 Dial lock function Lights when the dial lock function is ON The dial lock function prevents accidental frequency changes caused by inadvertently rotating the tuning dial. Push [LOCK] to toggle the dial lock function ON and OFF. · When the dial lock function is turned ON, the [LOCK] indicator lights red. [LOCK] 40 FUNCTIONS FOR RECEIVE 5 5-10 Twin PBT [TWIN PBT] The PBT function electronically narrows the receiver's IF passband widths to reduce interference. See the illustration below. · [TWIN PBT] should normally be set to the center positions when there is no interference. · Not available in FM mode. M1 AGC DUP CMP TCN SCP Twin PBT graphic indication PBT OPERATING EXAMPLE center passband passband IF shift pass band IF center frequency interference desired signal inteference desired signal IF center freq. interference 41 5 FUNCTIONS FOR RECEIVE 5-11 Selecting IF filters Optional filters can be installed in the IF stage of the IC-761 (p. When an optional filter is installed, set the optional filter setting using filter program mode (see below). Filters can be independently selected for each operating mode. FILTER CONSTRUCTION 9 MHz IF filter through FL-272 (2. 4 kHz) (standard) 9 MHz (optional 1) 9 MHz (optional 2) Mixer 455 kHz IF filter CFJ455k (2. 4 kHz) (standard) SFPC455G (9 kHz) (standard) SFPC-455E (15 kHz) (standard) 455 kHz (optional) 3rd LO · 9 MHz optional filters FL-101 (250 Hz) FL-232 (350 Hz) FL-100 (500 Hz) FL-223 (1. 9 kHz) FL-103 (2. 8 kHz) · 455 kHz optional filters FL-53A (250 Hz) FL-52A (500 Hz) FL-222 (1. 8 kHz) FL-96 (2. 8 kHz) FL-257 (3. 3 kHz) NOTE: one 455 kHz optional filter can be installed; two 9 MHz optional filters can be installed. s FILTER PROGRAM MODE SETTINGS Push [FILTER] for 2 sec. to select filter program mode. Push a mode key to select an operating mode for the filter setting. Push [FILTER] to set the filter condition to normal or narrow. · "NAR" appears when narrow is selected. Push [F2](9M) or [F4](455k) one or more times to select a 9 MHz filter or a 455 kHz filter, respectively. Repeat steps to to set filters for other operating modes, if desired. [FILTER] Push [MENU] to return to regular operation. NOTE: See p. 78 for activating the installed optional 9M 455k FIL 2. 4k - 2. 4k F1 F2 F3 F4 F5 filter(s). Selects 9 MHz band filter Selects 455 kHz band filter FIL 9M 455k 2. 4k - 2. 4k 42 FUNCTIONS FOR TRANSMIT 6-1 VOX function 6 The VOX function starts transmission without pushing the transmit switch or PTT switch when you speak into the microphone; then, automatically returns to receive when you stop speaking. Before using this function, follow the steps below. Select a phone mode (SSB, AM, FM). [. . . ] Make sure that [ANT1] is used for frequencies less than 60 MHz and [ANT2] is used for frequencies of 60 MHz and above. 17 The antenna is not properly tuned. The attenuator function is activated. 38 OFF. MAINTENANCE 14 PROBLEM Transmitting is impossible. POSSIBLE CAUSE The operating frequency is not set to a ham band. The split frequency function is turned ON with different bands in VFO A and VFO B. SOLUTION Set the frequency to a ham band. REF. p. [. . . ]