### Overview of the 2SA498-R Transistor The **2SA498-R** is a classic Silicon PNP epitaxial planar transistor. It was primarily designed for use in the driver stages of audio frequency amplifiers and for general-purpose high-voltage switching applications. --- ### 1. Key Technical Specifications The "R" suffix typically denotes a specific **hFE (DC Current Gain)** classification, ensuring the component falls within a narrowed range for circuit stability. | Parameter | Symbol | Rating | Unit | | :--- | :--- | :--- | :--- | | **Type** | - | PNP | - | | **Collector-Base Voltage** | $V_{CBO}$ | -80 | V | | **Collector-Emitter Voltage** | $V_{CEO}$ | -80 | V | | **Emitter-Base Voltage** | $V_{EBO}$ | -5 | V | | **Collector Current (DC)** | $I_C$ | -500 | mA | | **Collector Power Dissipation** | $P_C$ | 600 | mW | | **Junction Temperature** | $T_j$ | 150 | °C | | **DC Current Gain (hFE)** | $h_{FE}$ | 40 - 80 (R Rank) | - | --- ### 2. Pin Configuration (TO-92 Package) Looking at the flat side of the transistor with the leads pointing downwards, the pinout is typically as follows: 1. **Emitter (E)** 2. **Collector (C)** 3. **Base (B)** > *Note: Always verify with a multimeter or specific manufacturer datasheet as legacy parts can sometimes vary by region.* --- ### 3. Features and Usage * **High Voltage:** With a $V_{CEO}$ of -80V, it is suitable for circuits operating on higher voltage rails than standard small-signal transistors. * **Audio Applications:** Commonly found in the "Driver Stage" of vintage Hi-Fi audio equipment to drive larger power transistors. * **Complementary Pair:** It is often paired with the **2SC798** (NPN) for push-pull amplifier configurations. --- ### 4. Equivalent / Replacement Parts If the 2SA498-R is unavailable, the following transistors are often used as functional substitutes, though lead configurations may differ: | Replacement | Comparison | | :--- | :--- | | **2SA1013** | Higher current (1A), similar voltage. | | **KSA1013** | Modern equivalent, widely available. | | **BC556** | Lower voltage/current; only for low-power signal use. | | **BD140** | Higher power handling, requires different mounting (TO-126). | ---