Heathkit W4-AM Single-Chassis 20-Watt Amplifier Power Output: 20 watts RMS, Williamson-type circuit Frequency Response: ± 1 db from 10 to 100,000 cps at 1 watt Harmonic Distortion: 1.5% at 20 watts Intermodulation Distortion: 2.7% at 20 watts (60 and 3,000 cps, 4:1) Hum: 95 db below 20 watts Damping Factor: 28.5:1 Input voltage for 30 watts output: 2 volts Tube complement: (2) - 6SN7GT (2) - 5881 (1) - 5V4G Output Transformer: Chicago Standard, Special Design Output Impedance: 4, 8, 16 Ohms Power requirements: 105-125 volts, 50/60 cycles, 115 watts Dimensions: 15¼" by 8½" shelf space, 7" high (allow 1½" by 15¼" additional shelf space for cables and connections) Weight: 26 lbs