The **2SC1663** (often abbreviated as **C1663**) is a vintage NPN silicon epitaxial transistor. It was primarily manufactured by Sanyo and is designed for high-frequency applications, particularly in the radio frequency (RF) stages of telecommunications equipment. --- ### 1. Key Technical Specifications The C1663 is characterized by its ability to handle high frequencies with low noise, making it ideal for signal amplification. | Parameter | Symbol | Maximum Rating | | :--- | :--- | :--- | | **Collector-Base Voltage** | $V_{CBO}$ | 30 V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 20 V | | **Emitter-Base Voltage** | $V_{EBO}$ | 4 V | | **Collector Current (DC)** | $I_C$ | 30 mA | | **Collector Power Dissipation** | $P_C$ | 200 mW | | **Transition Frequency** | $f_T$ | 600 MHz (Typical) | | **DC Current Gain** | $h_{FE}$ | 40 to 200 | --- ### 2. Physical Characteristics and Pinout The device usually comes in a **TO-92** small plastic package, which is standard for low-power signal transistors. **Pin Configuration (Bottom View):** 1. **Emitter (E)**: The lead where current exits. 2. **Collector (C)**: The lead where current enters. 3. **Base (B)**: The lead that controls the transistor's conductivity. > *Note: Always verify the pinout with a multimeter or datasheet for the specific manufacturer, as vintage parts may have variations (e.g., Central Semi vs. Sanyo).* --- ### 3. Common Applications Due to its high transition frequency ($f_T$) of 600 MHz, the C1663 is utilized in specific electronic circuits: * **FM/VHF Amplifiers:** Used in the front-end of radio receivers to boost weak incoming signals. * **Local Oscillators:** Integrated into tuning circuits for RF communication. * **Mixer Stages:** Used to combine frequencies in superheterodyne receivers. * **Signal Switching:** High-speed low-current switching applications. --- ### 4. Equivalents and Replacements Since the original C1663 is an older part and may be difficult to source, the following transistors are often used as functional substitutes, provided the circuit parameters match: * **2SC1923:** Very common RF NPN transistor. * **KSC1663:** The Fairchild/ON Semi equivalent. * **2SC945:** (For general-purpose switching only; may not perform as well at high RF frequencies). * **BF199:** A common European RF alternative. --- ### 5. Circuit Symbol (NPN) ```text (Collector) | |/ (Base)-| |\> | (Emitter) ```