Triode
The RCA 812 Vacuum tube is a Power Output tube. It was
first developed by the Radio Corporation of America (RCA)
in 1924. It incorporates a UX-Base.
Type 812A is a variant of type 811 with a coarser grid
and a lower ì of 29. This meant that the negative grid
bias for Class C operation, and hence the RF input
voltage, had to be increased but the overall result was
slightly more efficient. A further variant (Type 812H)
had an even heavier anode construction, allowing 85W
dissipation and up to 225W of output when run at 1750V,
170 mA. However, this version was limited to 30 MHz and
was thus in competition with numerous other HF types.
Types 812/A/H were (and are) much less common than the
original type 811.
The anode box has channel sections added to form
radiator fins. The grid is wide spaced and made from
substantial gauge wire. This valve was used for low
frequency RF power amplification or as an AF modulator.
The filament is formed from Thoriated Tungsten wire and
is formed into a pair of inverted V's. The top of the
curves in the filament are held in tensioned hooks.
The large classic envelope is 58 mm in diameter and,
excluding the UX4 base pins, is 140 mm tall.
Electrical Data:
Heater Voltage .............................. 6 V
Heater Current ............................ 4.5 A
CV2661