The 304TL saw service during World War II and afterward as a modulator tube in radar sets. It has enormous filament emission and plate current capabilities. The plate resistance is in the 1,000 to 1,500 ohm range, depending on operating point. A pair of 304TLs in push-pull class A service can deliver over 700 watts of audio power at 3,000 volts. A single 304TL in class A service will deliver over 40 watts, depending on choice of operating conditions and plate load. The maximum rated plate dissapation is 300 W. The filament requirements of the 304TL are either 5 V at 25 A or 10 V at 12.5 A.
The lesser known and rarer 152TL is literally half of a 304TL and uses the same socket. The cute 75TL is one-fourth of a 304TL and uses a 4-pin medium base. At approximately 4,800 ohms plate resistance, the 75TL requires an output transformer with at least 75 H primary inductance to achieve -1 dB at 20 Hz.