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The 828 is a multi-electrode transmitting tube with a maximum plate-dissipation rating (ICAS) of 80 watts. The tube contains a suppressor and has beam power features. Because of its high power sensitivity, the 828 can be operated in r-f services to give full power output with very little driving power and, consequently, with a minimum of driver equipment. For example, in class C telegraph service, the 828 is capable of delivering 200 watts (ICAS) with only 2.2 watts of driving power! Neutralization is unnecessary in adequately shielded circuits. The tube is well suited for use in r-f applications as an r-f power amplifier, frequency multiplier, oscillator, and grid- or plate-modulated amplifier. It makes an excellent power amplifier for the final stage of medium-power transmitters where quick band-change without neutralizing adjustments is desirable. The 828 may be operated at maximum ratings at frequencies as high as 30 Mc and at reduced ratings up to 75 Mc.
The 828 is also well suited for use as a class AB1 modulator and a-f power amplifier. Two tubes in class AB1, CCS, are capable of delivering 300 watts of audio power with only 1% distortion!
The 828 is equipped with the "MICANOL" base having excellent insulating qualities at high frequencies, together with a low moisture-absorption characteristic. The plate connection of the tube is brought out through a separate seal at the top of the bulb to provide high insulation. The 828 contains a husky 32.5-watt thoriated-tungsten filament which has a great reserve of filament emission. |
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