The 6W4GT is a television efficiency diode with a 6.3 Volt heater for use with parallel heater connections. The electrically equal 25W4GT is designed for equipment with series heater chains.
The PIV rating is 3,850 Volts, peak current 750 mA and anode dissipation of 3.5 Watts.
The anode side view. What can be seen are the anode plates folded out at right angles to take up less space.
The anode plates are stitched together. The cathode to anode space is not large.
The dome carries the etched lettering.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 70 mm tall.
Reference: Data-sheet. Type 6W4GT was first introduced in 1950. See also1950 adverts.
