Characteristics
| Base | UX-Base (4 pins, 2 thick), A4-72 Medium 4-Pin Bayonet Base |
| Type | Triode Power Output |
| Filament | Vf = 5 Volts, If = 1.2 Ampere, Direct Specified voltage AC/DC |
| Identical | WE300B, 4300A, CV2609 |
| Similar | Slightly Different: PX300B Different Quality: 300B-98 |
| Predecessor | 300A |
Maximum Ratings
| Max Anode Voltage (Pin 2) | 400 Volts |
| Max Anode Current | 100 mA |
| Max Anode Dissipation | 36 Watts |
| Max Circuit Resistance for Fixed Bias | 0.05 MegaOhm |
| Max Circuit Resistance for Self Bias | 0.25 MegaOhm |
Pin Layout
| Pin | Function |
| 1 | Filament |
| 2 | Anode |
| 3 | Grid |
| 4 | Filament |