Icom IC-22U User Manual

Details general specifications of the transceiver, including semiconductor counts and frequency coverage.

Lists specifications related to the transmitter section, such as output power and emission mode.

Details specifications for the receiver section, including sensitivity and selectivity.

Instructions for unpacking the transceiver and checking for shipping damage.

Guidance on selecting a suitable location for mounting the transceiver.

Information on power supply needs and connection for mobile and fixed station use.

Advice on selecting and adjusting an antenna for optimal performance.

Details on connecting and using the supplied microphone.

Information on connecting an external speaker for enhanced audio output.

Overview of controls and indicators like thumbwheel switches, indicators, and connectors on the front panel.

Explanation of how the 1MHz thumbwheel switch sets the operating frequency.

Explanation of how the 100KHz thumbwheel switch sets the operating frequency.

Explanation of how the 10KHz thumbwheel switch sets the operating frequency.

Function of the Tone Call switch for repeater access.

Operation of the RF Power switch for selecting output power levels.

How the frequency shift switch affects transmit/receive frequencies.

Adjustment of the squelch threshold to minimize unwanted noise.

Operation of the volume control and integrated power switch.

Selection of Duplex or Simplex operation modes.

Configuration of transmit/receive frequency offsets for duplex operation.

Location and use of the microphone connector.

Functions of the S-meter and RF output level meter.

Function of the indicator that illuminates when squelch is open.

Function of the indicator that illuminates during transmission.

Identification of connectors and sockets on the rear panel, including antenna, power, and accessory ports.

Connection details for the antenna to the transceiver.

Location for connecting the power supply cord.

Port for connecting an external speaker.

Terminal for optional accessory circuits.

Steps to take before operating the transceiver, including connections.

Procedures for setting up and operating the transceiver in receive mode.

Procedures for setting up and operating the transceiver in transmit mode.

Diagram and labeling of components on the main circuit board.

Diagram and labeling of components on the PLL circuit board.

Overview of the transceiver's design principles and technology.

Explanation of the internal circuits for receiving signals.

Description of the audio signal processing path.

How the squelch circuit functions to suppress noise.

Explanation of the internal circuits for transmitting signals.

Theory behind the 16.9MHz oscillator and modulation process.

Explanation of the mixer circuit's function in frequency conversion.

Details on the power amplifier stage and its output filtering.

Theory of the audio frequency circuit, including IDC and filtering.

Explanation of the circuit that controls the transmitter's output power.

How the Automatic Protection Circuit (APC) prevents damage.

Explanation of how the S-meter and RF output meter operate.

Details on the transceiver's internal power supply distribution.

How the transceiver switches between transmit and receive modes.

Overview of the Phase-Locked Loop (PLL) circuit for frequency control.

Explanation of the Voltage-Controlled Oscillator (VCO) and its frequency conversion.

Details on the reference oscillator used in the PLL system.

Function of the phase comparator in the PLL loop.

Circuitry for muting the transmitter during certain conditions.

Explanation of the Tone Call unit for repeater access.

Voltage readings for transistors in the main unit.

Voltage readings for integrated circuits in the main unit.

Voltage readings for transistors in the PLL unit.

Voltage readings for PLL unit ICs during transmit.

Voltage readings for PLL unit ICs during receive.

Voltage readings for the Tone Call unit.