Sensibly equivalent¶ to:
The AC/SP3 is an indirectly heated HF pentode that employs the old UK standard heater rating of 4 Volts at 1 Amp. Mazda give the use as for Short Wave receivers and Television Sets and as a video amplifier it can modulate a cathode-ray tube. The advert states that the AC/SP3 features a special heater construction to reduce induced mains hum and making it suitable for the early stages of amplifiers.
The valve was graded on test into premium low hum A valves and the rest as grade B - fine for normal use. This exhibit has an A on the envelope.
The reverse is left as plain screening paint.
The classic envelope is 39 mm in diameter, and excluding the B7base pins is 111 mm tall.
References: Data-sheet & 1043. Type AC/SP3 was first introduced in 1937.
Absolute Maximum Operating Conditions¶
Updated January 05, 2019.