117Z3N — Single-Plate Diode Rectifier

An indirectly heated, single-plate vacuum diode designed for half-wave rectifier applications, featuring a line-voltage heater for transformerless operation.

Overview

The 117Z3N is a single-plate vacuum diode (diode monoplaque) designed for half-wave rectification (redresseur une alternance). It is characterized by a high-voltage heater rated at 117 V, which allows the tube's filament to be connected directly across standard AC power lines without requiring a step-down power transformer. The tube is constructed with an indirectly heated cathode, housed in a miniature glass envelope with a 7-pin base, and is rated for operation in any physical mounting position.

Physical Construction and Base Configuration

The 117Z3N is built using an A 19-4 glass bulb and a 7 C 10 base. The physical dimensions of the device are compact, with a maximum diameter of 19 mm and a maximum overall height of 60.3 mm. The pins extend from the base with a maximum length of 7.14 mm.

The tube utilizes a 7-pin layout with the following pin assignments, viewed from the bottom of the base:

The mounting position for this tube is completely unrestricted (quelconque), allowing for flexible physical orientation within a chassis.

Heater and Cathode Characteristics

The 117Z3N features an indirectly heated, coated cathode. The heater is designed for high-voltage, low-current operation to match standard line voltages:

Because the heater operates at a high potential relative to ground, the insulation between the heater and cathode is rated to withstand significant voltage stress. The maximum peak heater-to-cathode voltage ($V_{fk}$) limits are:

• Heater positive with respect to cathode: 165 V max
• Heater negative with respect to cathode: 330 V max

Maximum Ratings

The maximum ratings of the 117Z3N are established under the design-center system (système des limites moyennes). Operating the tube beyond these limits may impair its performance or shorten its operating life:

Normal Operating Conditions and Performance

In typical applications, the 117Z3N is configured as a half-wave rectifier feeding a capacitor-input filter. The standard operating parameters are defined as follows:

Under these standard operating conditions, the output rectified voltage ($V_{red}$) varies depending on the load current:

• At half load (45 mA): 120 V
• At full load (90 mA): 100 V

The minimum anode supply resistance of 15 \u0009\u000a is a critical parameter required to limit peak inrush and steady-state currents through the diode, protecting the cathode from damage when charging the 40 \u00b5F input filter capacitor.

Technical Summary

The 117Z3N is a compact, 7-pin miniature single-plate rectifier diode designed for efficient half-wave rectification. Its primary distinguishing feature is its 117 V, 40 mA heater, which permits direct line-voltage operation. With a maximum rectified current capability of 90 mA, a peak inverse voltage rating of 330 V, and a compact 19 mm diameter form factor, the 117Z3N provides a simple and space-saving solution for generating DC power directly from AC mains without requiring a power transformer.