The 300B is a directly heated audio power triode first introduced in around 1950 but the design of the equivalent 4300A dates to 1938.
In the 21st century the 300B is much appreciated for use in quality audio amplifiers both single ended and push-pull. It is one of the few Types still in production but these days manufacture is in China or Russia.
The anode dissipation is 40 Watts maximum and in single ended Class A can produce around 10 Watts of output depending on operating conditions. With a high negative bias the HT voltage for a self biased stage would be of the order of 500 Volts.
The Flanges on the anode add to the surface area for dissipating the heat generated in operation. In Class A this is constant dissipation.
The folded anode is stitched together.
The top view showing the four filament tension springs and the shape of the grid winding.
Here the oxide coated ribbon filament is visible and the grid wires look to be gold plated.
The classic envelope is 61 mm in diameter, and excluding the UX4 base pins is 133 mm tall.
Reference: Data-sheet. Type 300B was first introduced in 1949. See also1949 adverts.
