Similar medium-mu transmitting triode with comparable plate dissipation (75W); different base and filament — not pin-compatible
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Plate Voltage (max)3,000V
Anode Dissipation (max)Plate Dissipation (max)75W
Cathode Current (max)Plate Current (max)225mA
Typical Operating
Anode Voltage (typical)Plate Voltage (Class-C RF typical)1,500V
Notes
DHT tube: the thoriated-tungsten filament serves as the cathode; there is no heater-cathode isolation.
The 'TH' suffix denotes the high-mu variant (mu ~20); the 75TL is the low-mu variant (mu ~12).
Base is a medium 4-pin bayonet, ceramic, RMA type M8-078 (Johnson type No. 122-224, National type XC-4 or CIR-4). Physically larger than the standard UX4 used on receiving tubes.
Eimac HR-3 (plate) and HR-2 (grid) heat-dissipating connectors are recommended.
Maximum plate and grid seal temperature is 225°C.
Three Class-C RF typical operating points given: Va=1000V/Ia=215mA/Pout=140W, Va=1500V/Ia=167mA/Pout=175W, Va=2000V/Ia=150mA/Pout=225W.