50Y6GT

The 50Y6GT is a high-vacuum twin rectifier for AC and universal radio-receiver supplies. It contains two sections with separate cathodes for the rectifier and voltage-doubler circuits described by the maker. RCA’s brief February 1, 1950 sheet describes it as the same as 25Z6GT except for the heater. That is its distinguishing feature: 50 V at 150 mA AC or DC, rather than the 25 V at 300 mA of the 25Z6 family. Related rectifier sections do not imply identical heater-string requirements.

Tung-Sol’s June 6, 1941 sheet for 50Y6GT/G depicts a T-9 tubular glass envelope and an octal base, G-7Qa. The two sections may work separately or, in half-wave service, in parallel to reduce tube drop. Indirect heating and separate cathodes allow the sections to be arranged for the chosen circuit. The suffix and mechanical drawing should therefore be read alongside the electrical characteristics.

For half-wave rectification Tung-Sol lists a maximum DC current of 75 mA per anode. The three tabulated conditions use 117, 150 and 235 V RMS per anode with minimum total effective source impedances of 15, 40 and 100 Ω per anode respectively. For voltage doubling, both half-wave and full-wave, it gives 117 V RMS per anode and 75 mA maximum DC output, with minimum impedances of 30 and 15 Ω per anode respectively. Table AC voltages must not be mistaken for DC voltages available to the load.

Tung-Sol’s limits are 235 V RMS AC per anode, 700 V peak inverse voltage, 450 mA peak anode current per section and 350 V DC heater-to-cathode potential. Drop is specified as 22 V at a measurement current of 150 mA per anode, distinct from maximum DC output current. Curves show that rectified voltage and load current also depend on the filter input capacitance; above 40 µF extra supply impedance may be needed. This relationship between load, filter and source impedance explains why a doubler does not deliver an unchanging voltage in every condition.