Kenwood TR-2300 2m FM Handy Transceiver

General Information

The Kenwood TR-2300 is an all-solid-state 144 MHz band handy transceiver designed for amateur radio stations. It is compact, thin, and lightweight, with a transmitting output power of 1W and FM mode. The PLL frequency synthesizer system allows for transmission and reception on 80 channels, with a 25 kHz separation, selectable via a 40-position rotary switch.

Circuit Description

The TR-2300 comprises several key units:

• RX SYNTHESIZER unit: X55-1220-61
• TX unit: X56-1280-00
• FILTER unit: X51-1160-00
• TONE unit: X52-1110-61 (W type) or X52-1110-50 (T type)

Accessory circuits include an S/RF meter, battery checker, squelch circuit, Aux circuit, TONE OSC circuit, lamp indicator circuit, and a frequency shift circuit (Repeater). Accessory terminals are provided for whip antenna, external antenna, microphone, external DC power, and external speaker.

Receiver Circuit: Received signals are amplified by an RF amplifier (Q1) and fed to the first mixer (Q2). The receiver features two tuning circuits and a helical resonator for improved bandwidth and rejection of out-of-band signals and cross-modulation. The first oscillator signal (133 MHz band) from the PLL circuit is mixed with the received signal to produce a 1st intermediate frequency of 10.7 MHz. This signal passes through an MCF and is amplified by Q3, then fed to Q4, which includes a limiter circuit, second oscillator, mixer, discrete circuits, and a squelch circuit. An AF signal from Q4 is amplified by Q5 and sent to Q16 for power amplification. Part of the second intermediate frequency is used to operate the S-meter.

Transmitter Circuit: Audio signals from the MIC terminal are amplified by Q9 for modulation. A crystal oscillator (Q1) generates a 10.7 MHz signal, which is used for variable reactance direct shift. The amplified signal from Q2 is mixed with the 133 MHz band signal from the PLL circuit to produce a 144 MHz band signal. This signal is amplified through several stages, including a power amplifier (Q7), with an ALC circuit ensuring stable output.

PLL Circuit: The PLL circuit utilizes a Phase-Locked Loop system for frequency synthesis. It features a VCO with temperature compensation and power stabilization. The VCO output is mixed with a local oscillator signal (129.6999 MHz) to produce an IF signal (3.60 to 4.575 MHz). This IF signal is prescaled and fed to a programmable divider (CMQS LSI), which compares its output with a reference oscillator signal (12.80 MHz) to control the VCO frequency. The programmable divider ratio (N) is set by the main knob, typically between 144 and 183, to achieve a 12.5 kHz output.

Data

Semiconductor Data:

• MC3357: A low-power FM IF circuit designed for voice communication scanning receivers. It integrates an oscillator, mixer, limiter amplifier, quadrature FM detector, squelch trigger circuit, and audio output buffer.
• SM5104GA: A C-MOS LSI for PLL applications, featuring a reference oscillator, divider, amplifier, programmable counter, and phase detector.

Crystal Quartz (AUX Channel): Specifications for crystal quartz used in AUX channels are provided, including type (HC-25/μ), frequency calculation formula ($fo = (f - 13.90) / 3$), allowable frequency deviation, and temperature range.

Filter (L72-0309-05): Specifications for the ceramic filter include nominal center frequency (455 kHz), bandwidths (3 dB, 6 dB, 60 dB), guaranteed attenuation, ripple, insertion loss, and input/output impedance.

Performance Characteristics: Graphs illustrate Intermodulation Characteristics, Sensitivity Suppression Characteristics, and Spurious Response.

Parts Alignment

Diagrams show the front panel and internal components of the TR-2300, with labels for various parts such as knobs, switches, jacks, S-meter, LED, and internal units like the Filter unit, RX synthesizer unit, Battery housing, TONE unit, and TX unit.

Printed Circuit Board Layouts

Detailed layouts of the Printed Circuit Boards (PCBs) for the RX Synthesizer Unit (X55-1220-61), TX Unit (X56-1280-00), Filter Unit (X51-1160-00), and TONE UNIT (X52-1110-50 T TYPE) are provided, showing component placement and connections.

Parts List

Extensive parts lists are provided for each unit (RX Synthesizer, TX, Filter, Tone) and miscellaneous components, including capacitors, resistors, semiconductors, potentiometers, switches, coils, inductors, IFTs, crystals, and case/panel components.

Packing

An illustration shows the packing procedure for the TR-2300, detailing the placement of the transceiver, operating manual, and accessories within the carton case.

Disassembly

Exploded view diagrams illustrate the disassembly process for the front panel and other components, with numbered parts corresponding to the parts list.

Troubleshooting

Flowcharts and descriptions guide the user through troubleshooting common issues such as no transmission or reception, no RF meter indication, no S-meter indication, noise issues, distorted sound, and battery charging problems. Specific component failures and potential causes are listed.

Level Diagram

Schematic diagrams with voltage levels indicated at various test points are provided for the Receiver Section and the Synthesizer (PLL) Section. Measuring conditions and required test equipment are also detailed.

Adjustment Procedures

Detailed step-by-step procedures are outlined for various adjustments and alignments, including:

• Voltage and Lamp Operation Checks
• Battery Checker Adjustment
• PLL Circuit Adjustments (frequency and voltage checks)
• RX Unit Adjustments (RF unit and IF circuit alignment, S-meter adjustment)
• TX Unit Adjustments (transmitting output power, RF meter, transmitting frequency, modulation factor, tone unit adjustment)

These procedures require specific test equipment such as SSG, RF valve voltmeters, power meters, oscilloscopes, and frequency counters.

Options and Accessories

• Trickle Charger [BC-1]: Specifications for the battery charger, including input voltage, power consumption, and output current/voltage.
• Nickel-Cadmium Battery Pack [PB-15]: Details on the battery pack, its composition, specifications (voltage, capacity, charging current/time), and operating temperature ranges.
• Helical Whip Antenna [RA-1]: Specifications for the antenna, including type, frequency range, impedance, operating temperature, and dimensions.

Block Diagram and Schematic Diagram

A comprehensive block diagram illustrates the overall functional blocks of the TR-2300, showing interconnections between units. A detailed schematic diagram provides the complete circuit layout, including component designators and values.

Specifications

A summary of the TR-2300's general, transmitter, and receiver specifications is provided, including:

• General: Component count (transistors, FETs, ICs, diodes), frequency range, operating temperature, standard operating voltage, antenna impedance, DC current consumption, dimensions, and weight.
• Transmitter Section: Frequency range, mode, RF output power, modulation type, maximum frequency deviation, spurious radiation, and microphone specifications.
• Receiver Section: Receiving frequency, mode, circuitry (double superheterodyne), intermediate frequencies, sensitivity, squelch sensitivity, pass band width, selectivity, and audio output power.