Genuine Motorola MRF652 RF Power Transistor for Transmitter Final Amplifier
The Motorola 4805474G49 is a high-performance MRF652 RF power transistor designed for professional repair and maintenance of Motorola radio transmitter equipment. This genuine OEM semiconductor component provides reliable high-power amplification in VHF and UHF transmitter final stages. The stud-mount package with beryllium oxide ceramic insulator ensures excellent thermal dissipation for demanding continuous-duty applications.
Key Features
- Genuine Motorola factory replacement part - ensures exact specifications and reliable RF performance
- MRF652 designation for high-power RF amplification applications
- Stud-mount package with threaded base for secure heatsink mounting
- Beryllium oxide ceramic insulator for superior thermal conductivity
- Gold-plated leads for RF performance and corrosion resistance
- High power output capability for VHF/UHF transmitter stages
- Designed for continuous-duty commercial and professional radio service
Compatible Models
- Various Motorola VHF and UHF commercial two-way radio transmitters
- Used in final amplifier stages and RF power output circuits
- Consult your radio's service manual or schematic diagram for exact component specifications
What's Included
- One (1) Motorola MRF652 RF power transistor
Application and Installation
Professional Installation Required - High Voltage and RF Power Component: This RF power transistor operates at high voltages and handles significant RF power levels. Installation, alignment, and testing should only be performed by qualified RF technicians or certified Motorola service centers with proper RF test equipment, including RF power meters, spectrum analyzers, and dummy loads. Improper installation can result in component failure, reduced transmit power, spurious emissions, or damage to other radio components.
Critical Thermal Management: RF power transistors generate substantial heat during transmission and require proper thermal management for reliable operation. The transistor must be mounted to an adequate heatsink with proper thermal interface material. Clean both the transistor mounting surface and heatsink thoroughly before installation. Apply a thin, even layer of thermally conductive compound to ensure maximum heat transfer. Torque the mounting stud to manufacturer specifications to achieve proper thermal contact without over-stressing the ceramic insulator.
Installation Procedure: Before installation, discharge all power supply capacitors and ensure the radio is completely powered down. Mount the transistor securely to the heatsink with appropriate thermal compound. Solder the RF input and output leads carefully to avoid overheating the component. The gold-plated leads should be kept short to minimize parasitic inductance. Ensure proper lead dress and spacing to prevent unwanted coupling or oscillation.
Testing and Alignment: After installation, carefully verify all bias voltages before applying RF drive power. Start with reduced drive power and gradually increase while monitoring collector current, output power, and harmonic content. Adjust input and output matching networks according to service manual specifications. Use a calibrated RF power meter and dummy load for all testing. Monitor transistor temperature during extended transmit periods to ensure adequate cooling.
Safety Warning
Beryllium Oxide Hazard: This transistor contains beryllium oxide ceramic, which is safe during normal use but can be hazardous if the ceramic is broken, crushed, or machined. Do not break, grind, or machine the ceramic insulator. If the ceramic is damaged, avoid creating or inhaling dust. Handle damaged components carefully and dispose of properly according to local regulations for beryllium-containing materials.
When to Replace
RF power transistors can fail due to excessive drive power, improper bias, inadequate cooling, high VSWR operation, or age-related degradation. Symptoms of transistor failure include no transmit output, reduced power output, distorted audio, excessive current draw, or overheating. Always investigate the cause of failure before installing a replacement transistor. Check bias circuits, drive levels, impedance matching, cooling systems, and load VSWR.
Technical Specifications
- Type: RF Power Transistor (NPN)
- Part Number: MRF652
- Package: Stud-mount with beryllium oxide ceramic insulator
- Mounting: Threaded stud for heatsink attachment
- Terminals: Gold-plated RF leads
- Application: VHF/UHF transmitter final amplifier
Part Numbers
- Motorola Part Number: 4805474G49
- Component Designation: MRF652 RF Power Transistor
- Package Type: Stud-mount with beryllium oxide insulator
