144-145 MHz (2-Meter) VHF Power Amplifier with GI-46b Tube – 500W

Technical Specifications

• Operating Frequency: 144 - 145 MHz (2-Meter Band)
• Active Component: 1 x GI-46b (ГИ-46б) Vacuum Tube
• Input Power (Drive): 35 W
• Output Power: 500 W
• Power Supply: Configured for an external anode power supply, which helps keep the amplifier unit compact, reduces chassis weight, and isolates heat generation.

Operational Capabilities & Supported Modes

This amplifier was designed and assembled with modern VHF DXing in mind. Because the GI-46b tube is highly resilient and the chassis features a well-engineered cooling system, the amplifier maintains outstanding thermal stability and linearity under heavy loads.

It is perfectly suited for traditional SSB (Single Sideband) voice communications, but it truly shines when used for high duty-cycle digital modes. The amplifier comfortably handles continuous wave and digital operations, including FT8, FT4, and MSK144 meteor scatter. Furthermore, with a solid 500 watts of output power, this unit provides the necessary RF punch required for weak-signal EME (Earth-Moon-Earth / Moonbounce) communications.

Build and Construction Details

As seen in the project photos, the amplifier features a clean, compartmentalized chassis layout designed to minimize RF interference.

• RF Deck & Cooling: The high-voltage components and the RF section are neatly organized. A dedicated high-throughput fan is mounted directly inline with the GI-46b to force air through the tube’s anode radiator, ensuring safe operating temperatures even during prolonged digital mode transmissions.
• Power Management: The internal layout features a heavy-duty capacitor bank and robust, custom-wound transformers for the filament and control voltages, while the high-voltage anode supply is kept external.
• Front & Rear Panels: The front panel is equipped with clear, easy-to-read analog metering for precise tuning (TUNE/LOAD controls). The rear panel provides standard UHF connectors for RF IN/OUT, a PTT control interface, and a heavy-duty multi-pin connector for the external power supply.