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The 25Z5 is an American TV rectifier. Within the envelope, sharing a common heater, are two independent rectifiers. The heater current of 0.3 Amps is one of the standard heater chain currents.

The independent rectifiers make three configurations possible: the pair as a full wave rectifier, the pair to produce 250 V from 117 V mains in voltage doubler configuration, and lastly in parallel as a half wave rectifier.

The valve lacks identification apart from the Philco name on the base. Visual inspection with other rectifiers suggested the 25Z5. Checking the heater at 0.3 Amp registered the correct temperature of the heater when 25 Volts were applied.

The maximum reservoir capacitor is quoted at 16 µF.

See also 25Z6G and 25Z6GT for IO based versions.

The twin anodes above the mica and two cathode connections below.

The top mica showing the pair of round cathode tubes and below the bottom mica the cathode connections fly away to the left.

The classic envelope is 38 mm in diameter and, excluding the UX6 base pins, is 89 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type 25Z5 was first introduced in 1936. See also 1936 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.