The 7D6 is an audio output pentode. A family of three valves that differ only in heater requirements exists: 7A3 - 4.0 V @ 2.0 A, 7D8 13 V @ 0.65 A and this valve with a 40 Volt heater.
The anode load should be 8,500 Ω with 250 Volt HT.
The Brimar logo.
The lower mica, pinch and connections. The inner structure is more clearly seen in the 7D8.
The classic envelope is 44 mm in diameter, and excluding the B7 base pins is 100 mm tall.
References: Data-sheet, & 1043. Type 7D6 was first introduced in 1935. See also1935 adverts.
