Classification-Dome-type or Aubergine-type bulb of glass, a four-prong bayonet pin tube,comprises to oxide coated filamentary diode units with a common filament.

Application-It is designed to supply direct current up to 200 milliamperes from an alternating current source.
Dimensions-Dimensions, outline diagrams of the tube and bases, and the arrangement of electrode connections to the base terminals are shown in Figures 1, 2 and 3.

Nominal operating conditions and parameters
Filament voltage………………………………………………………………5.0 V*
Nominal filament current……………………………………………………2.0A

Choke-Input filter
R-M-S Alternating voltage prelate …………………………………550V
Tolal rectified current………………………………………………160 mA

Condenser-Input Filter
R-M-S Alternating voltage prelate…………………………………………450V
Tolal rectified current………………………………………………………140mA

*Alternating-current filament supply or Direct-current filament supply.

Characteristics-Average characteristics

The current-voltage characteristic of a single diode untie of the 274A/B tube is shown in Figure 4.Direct-voltage output characteristics are given in Figures 5 and 6.The characteristics of figure 5 are for a choke-input filter such as is shown in circuit A and those of Figure 6 are for a condenser-input filter such as is shown in circuit B

Limiting Operation Conditions for Sate Operation:

Choke-input Filter:

I.Max.R-M-S Alternating Voltage per plate…………………………550 V
I. Max Total Rectified Current……………………………………….200mA
II.Max.R-M-S Alternating Voltage per plate…………………………660 V
II.Max. Total Rectified Current………………………………………160mA
Condenser-input Filter:

I.Max.R-M-S Alternating Voltage per plate…………………………450 V
I.Max. Total Rectified Current……………………………………….150mA

*4uF.Maximum filter input capacitance