Sensibly equivalent¶ to:
Type EL821 is a video output amplifier used in professional applications for driving TV or radar signals down (fairly) long cables. This exhibit is by Philips and made in Holland.
Sources specifically list it as a video amplifier for high definition television. Note the high value of gm, necessary in order to obtain reasonable gain and power output with wide-band signals, and for correct matching of video into coax cable. TV studio equipment racks used to be full of these valves.
The anode side view.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 59 mm tall.
References: Data-sheet & 1040. Type EL821 was first introduced in 1962.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated August 27, 2019. shape:thin.glass.tube construction:all.glass type:beam.tetrode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.ic pin:2.g1 pin:3.k pin:4.h pin:5.h pin:6.- pin:7.a pin:8.g2 pin:9.g3