The **2SC2668-R** is a NPN epitaxial silicon transistor specifically designed for high-frequency applications, primarily used in the local oscillator and mixer stages of FM/VHF tuners. --- ### 1. Key Technical Specifications The "R" suffix typically denotes the **hFE (DC Current Gain)** classification, which falls within a specific range. | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | 30 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 25 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | 4 | V | | **Collector Current** | $I_C$ | 20 | mA | | **Power Dissipation** | $P_C$ | 100 | mW | | **Transition Frequency** | $f_T$ | 550 (Typ.) | MHz | | **DC Current Gain** | $h_{FE}$ (R) | 40 to 80 | - | --- ### 2. Physical and Pin Configuration The device is usually housed in a **TO-92 (Mini)** or **SOT-23** (surface mount) package, depending on the manufacturer (commonly Toshiba). **Pinout (Front View - TO-92):** 1. **Emitter** (E) 2. **Base** (B) 3. **Collector** (C) --- ### 3. Application Areas Due to its high transition frequency ($f_T$) and low noise characteristics, it is optimized for: * **VHF Oscillators:** Stable frequency generation in FM radio circuits. * **Mixer Stages:** Combining RF signals with local oscillator signals. * **High-Frequency Amplifiers:** Small signal amplification in the 100MHz+ range. --- ### 4. Equivalent and Replacement Parts If the 2SC2668-R is unavailable, the following transistors are often used as functional equivalents (always check pinouts as they may differ): | Part Number | Primary Similarity | | :--- | :--- | | **2SC1923** | High-frequency performance (VHF) | | **KSC2668** | Direct cross-reference (Fairchild/Onsemi) | | **BF199** | Common European RF NPN transistor | | **2SC2498** | Higher frequency capability | --- ### 5. Circuit Symbol (NPN) ```text C (Collector) | |/ --B-| (Base) |\> | E (Emitter) ```