The 715A is a hard vacuum pulse amplifier tetrode. An earlier version was Type 701A and the successor to the 715A was the 715B.
The 715A was designed for use in airborne radar modulators and the heater rating was for use with the standard 24 Volt aircraft batteries where the voltage could vary from 22 to 28.5 volts. The anode voltage was up to 14,000 Volts and the peak pulse current was 10 Amps. The four parallel cathodes being required for sufficient electron production.
The lettering on the glass is both etched as her and printed as can be seen above. Both grids have heat radiating fins above and below the ceramic supports.
The B4A base. The envelope is of all-glass construction with the base pins passing through the glass. However, for stability and ease of location, the pins are held in a ceramic plate with locating notch and then capped with large ends that are fixed firmly into the ceramic disc.
The top of the valve. The diamond shaped holes in the ceramic top plate locate and secure the cathode tubes. The active length of each cathode is elliptical and oxide coated.
The wide glass tube envelope is 63 mm in diameter, and excluding the B4A base pins is 133 mm tall.
