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General| Brand | Barrett |
|---|---|
| Model | 980 |
| Category | Transceiver |
| Language | English |
Details receiver, exciter, audio processing, and I/O interface.
Explains power sampling, ALC detector, and voltage generation.
Describes protection circuitry including transorbs and diodes.
Covers microprocessor, synthesiser, selcall, mute, and power control functions.
Describes the microprocessor's control program execution and memory interfaces.
Explains frequency synthesis, local oscillators, and VCO operation.
Explains calibrating voltage for selcall phase lock and PA ALC.
Describes mixers, IF amplifiers, filters, noise blanker, and AGC.
Covers second IF amplifier, AGC generation, and demodulation.
Details audio routing, processing, tailoring, and I/O handling.
Describes Rx audio amplification, mute gate, VCA control, and speaker drive.
Describes display refresh, serial data, and LED status indicators.
Details the 20-function keypad, PWM encoding, and serial output.
Describes volume control, on/off switch, and power relay activation.
Covers replacing components, observing polarity, and lead removal.
Provides troubleshooting steps for no power issues, including voltage checks.
Troubleshooting steps for no receive audio despite display indications.
Checks for audio mute, selcall mute, and audio path issues.
Troubleshooting steps for LO faults, phase lock issues, and AGC.
Addresses issues with initial banner display and serial data path.
Checks for microprocessor activity or LCD module faults.
Covers EPROM/GAL fitment, LED checks, and oscillator signal issues.
Troubleshooting PLL, square waves, and charge pump transistor issues.
Steps to diagnose transmitter issues including signal injection and fuse checks.
Details transistor checks, removal, and thermal compound replacement.
Covers adjustments for the PA PCB.
Details driver bias adjustment using RV3 and current monitoring.
Covers PA bias adjustment using RV2 and PA current monitoring.
Guides setting RV4 for power level using test equipment.
