The Mazda AC/HL is an indirectly heated audio amplifier triode and the design dates to 1929. These valves were rugged and had long service lives. In the late 1920s and early 1930s Mazda produced the leading indirectly heated valves. The AC/Pen of 1930 set the standard that others followed.

From the top of the dome the rear wing of the anode can be seen.

The short path construction method is visible in this picture. The anode wings and the closely wound grid are defining features.

See also AC/HL

The balloon envelope is 56 mm in diameter and, excluding the B4 base pins, is 109 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a	g	h	h	k

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	4.0	1.0	200	-3.5	5.0	12,500	2.8

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 02 December 2007 {find valves by name}