The **2SC2791-R** is a High-Frequency NPN Epitaxial Silicon Transistor. It is primarily designed for high-frequency amplification and oscillation applications, common in radio frequency (RF) circuits. --- ### 1. Key Technical Specifications The "R" suffix typically denotes the **hFE (DC Current Gain)** classification, ensuring the part falls within a specific performance range. | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | 30 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 20 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | 3 | V | | **Collector Current (DC)** | $I_{C}$ | 30 | mA | | **Gain Bandwidth Product** | $f_{T}$ | 1.1 (typ) | GHz | | **DC Current Gain (R Grade)** | $h_{FE}$ | 40 – 80 | - | --- ### 2. Physical Characteristics The C2791 is usually manufactured in a small surface-mount package or a standard through-hole package depending on the specific manufacturer (often **TO-92** or **SOT-23** variants). * **Polarity:** NPN * **Material:** Silicon * **Frequency Range:** VHF / UHF (Very High to Ultra High Frequency) --- ### 3. Common Applications Due to its high gain-bandwidth product ($f_{T}$), this transistor is found in specific electronic modules: 1. **RF Amplifiers:** Used in the front-end of radio receivers to boost weak signals. 2. **Local Oscillators:** Integrated into tuning circuits for FM/AM or TV tuners. 3. **Signal Mixers:** Used in heterodyne circuits to convert high frequencies to intermediate frequencies (IF). 4. **Signal Switching:** High-speed switching in communication equipment. --- ### 4. Circuit Symbol Representation In a schematic, the 2SC2791-R is represented by a standard NPN bipolar junction transistor (BJT) symbol: ```text Collector (C) | --+-- / \ Base--| -> | (B) \ / --+-- | Emitter (E) ```