2SC2078 Final Power Transistor

The 2SC2078 is an NPN silicon epitaxial planar power transistor primarily designed for RF power amplifier applications at 27 MHz, and is commonly used as a final output transistor in CB radios.
2sc2078 C2078 in-Line to-220 NPN High-Frequency Power …
Key Specifications
According to various sources including manufacturers like Sanyo and HuaGao, the 2SC2078 has the following key specifications:
Transistor Type: NPN silicon epitaxial planar transistor.
Collector-Emitter Voltage (Vceo): 75V.
Collector Current (Ic): 3.0 A.
Power Dissipation (Ptot/Pc): 10 W (at a case temperature of +50°C).
Transition Frequency (fT): 150 MHz.
DC Forward Current Gain (hFE): 25-200 at Vce=5V, Ic=0.5A.
Package Type: TO-220AB, a standard through-hole package.
Common Applications
The 2SC2078 is used in applications that require high frequency and power handling capabilities:
CB (Citizens Band) Transceivers: Frequently utilized in the final amplifier stage of CB radios, such as the Cobra 29LTD, Cobra 25LTD, and many Uniden models.
HF (High Frequency) Transmitters: Used in the power amplifier stage of amateur radio equipment and HF transmitters due to its good gain characteristics.
RF Amplifiers: Due to its efficiency at frequencies up to around 30 MHz, it is used in various general RF amplifier circuits.
Audio Power Amplifiers: Can also be found in some audio power amplifier circuits.
Switching Regulators: Used in high-speed switching applications.
Replacements
The 2SC2078 can often be exchanged for other transistors in specific applications, such as the 2SC2166 and 2SC2029 in some CB radio applications. It can also sometimes be replaced by a 2SC1969, though this requires adjusting the biasing resistors.