S-31A
| Brand | Hallicrafters |
| Manufacturer | The Hallicrafters Co. |
| Function | Amplifier, Power |
| Produced | 1941-1942 |
| Country | United States |
| Form Factor | 19" Rackmount |
| Signal Path | Analog Hardware |
| Dimensions | 48.3 × 22.2 × 25.4 cm (W × H × D) |
| Power | 100W |
| Frequency Response | 50Hz-15kHz ±2dB |
| Output Power | 25W |
| Gain (Phono) | 60dB |
| Gain (Mic) | 96dB |
| Output Impedance | 4/8/500Ω |
| MSRP (1942) | $54 |
| Channels | 1 Channel |
| Notes | Intended for use with S-31 AM/FM tuner. Also came in RSC-2 Broadcast Receiving Station for PA installation. |