1802 — Half-Wave High-Vacuum Rectifier

Overview

The 1802 is a half-wave high-vacuum rectifier valve designed primarily for use in alternating current (A.C.) mains receivers. It features a directly heated filament and is housed in a glass envelope with an H32 base. The device is engineered to provide rectified high-voltage direct current (D.C.) from an A.C. supply, supporting a maximum A.C. anode voltage of 250 V and delivering up to 30 mA of rectified output current.

Construction, Filament, and Base

The 1802 is constructed as a single-plate (monoplaque) high-vacuum diode. It utilizes a directly heated filament, which operates at a nominal voltage of 4.0 V. Depending on the manufacturing variant, the filament current is approximately 0.4 A or 0.5 A.

The physical dimensions of the valve are characterized by a maximum overall length of 92 mm (specified in some contexts as excluding pins) and a maximum diameter of 46 mm to 47 mm. The tube is fitted with an H32 base, with connections designated as S V or reference 14.

Maximum Ratings

To ensure reliable operation and prevent damage to the valve, the operating conditions must be kept within the specified maximum limits. The absolute maximum ratings for the 1802 rectifier are:

• Maximum A.C. Anode Voltage (Va max): 250 V (also specified as 250 V_RMS no-load)
• Maximum Rectified D.C. Current (Ia max): 30 mA

These limits define the boundary conditions for safe operation in typical A.C. mains receiver power supplies.

Rectification Characteristics and Performance Curves

The performance of the 1802 under load is defined by the relationship between the rectified output voltage (Vd) and the rectified output current (Ia) across various effective A.C. input voltages (Veff).

As the current load increases, the internal resistance of the high-vacuum diode causes a drop in the rectified output voltage. The typical output characteristics at three distinct effective input voltages are:

These values demonstrate the regulation behavior of the rectifier. For instance, at an input of 250 V, drawing the maximum rated current of 30 mA results in a rectified D.C. voltage of approximately 210 V.

Technical Summary

The 1802 is a directly heated half-wave high-vacuum rectifier designed for A.C. mains receivers. Operating with a 4.0 V filament supply drawing 0.4 A to 0.5 A, it provides a reliable rectified D.C. output of up to 30 mA from an A.C. anode supply of up to 250 V. Housed in an H32-based envelope with a maximum length of 92 mm, the 1802 offers predictable voltage regulation characteristics across its operating range, making it a standard component for low-power high-voltage rectification in historical receiver designs.