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The 833A is a directly heated HF power triode with a thoriated tungsten filament. With forced air cooling and a drive of 38 Watts the 833A can produce up to 1,000 watts of RF power. The maximum frequency of operation at full power is 30 MHz. This covers the whole HF band.

The 833A is rated for service as a modulator and audio amplifier and a pair in class B can generate up to 2,700 watts. At maximum power the anode will glow an orange-red colour. Mounting requires care but can be horizontal or vertical.

RCA gave tentative data for the 833 in 1938. We do not have introduction data for the A variant as yet.

The top of the envelope carries the identification for Grid and anode etched into the glass. The internal supports are made from ceramic. The valve would have been pumped to a hard vacuum and is not gettered. At high RF voltages the gettering is a liability.

Thanks to Jonathan Edwards for the images and the measurements.

The wide glass tube envelope is 102 mm in diameter, and excluding the base pins is 169 mm tall. The overall length including the pins is 225 mm. The anode connections are 62 mm apart and the filament pins are 42 mm apart.

References: Data-sheet & ⁴⁰⁶¹.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.