Sensibly equivalent¶ to:
The 6X4 HT rectifier follows the normal pattern for a full wave device in that a common cathode is employed. This exhibit has the inside of the glass coated which is unusual in a rectifier. Normally such a coating reduces gas release from the glass caused by electron bombardment but perhaps with a B7G based rectifier, fitted inside a small diameter glass tube, the need is to increase the amount of heat radiated away from the valve.
At 325-0-325 input to the rectifier this will give an HT rail higher than is required for most domestic receivers. Use for audio amplifiers and small transmitters is most probable, or driven at 250 volts for radio receivers.
The 12X4 is electrically identical and was developed for use with vibrator power supplies in car radios.
The thin glass tube envelope is 18 mm in diameter and the length, excluding the B7G base pins, is 59 mm.
References: Data-sheet & 1040.
Absolute Maximum Operating Conditions¶
Updated March 12, 2022.