Western electric 404 a brochure

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BELL SYSTEM PRACTICES ' A1346. 2+01TA
Transmission Engineering and Data Issue 2 , November 1955
Electron Tube Data A.T.&T. Co. Standard

ELECTRON TUBE DATA SHEET
WESTERN ELECTRIC 404A ELECTRON TUBE

DESCRIPTION

The hOhA electron tube is an indirectly heated cathode type miniature pentode.
It is intended primarily for use in high-gain amplifiers at high and very high
frequencies .

CHARACTERISTICS

Heater Voltage ........................ 6.3 volts
Cathode Current. . Eb = 150 volts; Ec2 = 150 volts . . . . 17.5 milliamperes
Transconductance . Ecol = 0; Rk = 110 ohms 13500 micromhos

File: Miniature Section
Issue 3, 11-55

404A

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QOQA - Page 2

GENERAL CHARACTERISTICS
ELECTRICAL DATA
Heater Voltage . . . . . . . . . . . . . . . . . . . . . . . 6.3 volts
Heater Current . . . . . . . . . . . . . . . . . . . . . . . 300 milliamperes
Direct Interelectrode Capacitances Without With External
External
Shield
Grid to Plate (maximum) . . . . . . 0.05
Input: gl to (h+k+g2+g3+i.s.) . . . 7.0
Output: 9 to (h+k+32+33+i.s.) . . . 2.;
MECHANICAL DATA
Cathode . . . . . . . . . . . . . . . . . . . . . . Coated Unipotential
Bulb . . . . . . . . . . . . . . . . . . . . . . . T6 1/2
Base . . . . . . . . . . . . . . . . . . . . . . . Small Button, 9-Pin
Mounting Position . . . . . . . . . . . . . . . . . Any
Dimensions and Pin Connections . . . . . . . . . . See Outline Drawing-Page A
MAXIMMH RATINGS, Design-Center Values
Plate Voltage . . . . . . . . . . . . . . . . . . . . . . . . 250 volts
Screen Grid Voltage . . . . . . . . . . . . . . . . . . . . . 150 volts
Plate Dissipation . . . . . . . . . . . . . . . . . . . . . . 3 watts
Screen Grid Dissipation . . . . s . . . . . . . . . . . . . . 0.75 watt
Control Grid Dissipation . . . . . . . . . . . . . . . . . . See footnote *
Cathode Current . . . . . . . . . . . . . . . . . . . . . . 35 milliamperes
Heater-Cathode Voltage . . . . . . . . . . . . . . . . . . . 50 volts
Bulb Temperature . . . . . . . . . . . . . . . . . . . . . . 120° centigrade
MAXIMUM CIRCUIT VAIUES
Grid Circuit Resistance:
For Fixed Bias . . . . . . . . . . . . . . . . . . . . . 50000 ohms
For Cathode Bias . . . . . . . . . . . . . . . . . . . . 100000 ohms

TYPICAL OPERATING CONDITIOKS AfiD CHARACTERISTICS

Plate Voltage . . . . . . . . . . . . . . . . . . 130 150 volts
Screen Grid Voltage . . . . . . . . . . . . . . . 130 150 volts
Control Grid Supply Voltagel . . . . . . . . . . +7.5 --- volts
Cathode Bias Resistorl . . . . . . . . . . . . . 430 110 ohms
Plate Current . . . . . . . . . . . . . . . . . ; 15.5 lh.0 milliamperes
Screen Grid Current . . . . . . . . . . . . . . . h.5 3.5 milliamperes
Plate Resistance . . . . . . . . . . . . . . . . 95000 90000 ohms
Transconductance . . . . . . . . . . . . . . . . thOO 13500 micromhos
Control Grid Voltage (approximate) for

Plate Current of 10 Microamperes . . . . . . . - h.3 -5.0 volts
Modulation:

Second Order (2F)** . . . . . . . . . . . . . . A3 A6 db

Third Order (3F)*** . . . . . . . . . . . . . . 21 28 db

Load Resistance . . . . . . . . . . . . . . . 200 200 ohms

* Operation with the control grid positive with respect to the cathode is not
recozmended.

** Ratio of product to fundamental at output for 0.1 volt rms signal from grid
to cathode.

*** Ratio of product to fundamental at output for a 0.2 volt rms signal from
grid to cathode.

Note 1: Reference point for control grid voltage is the negative end of the cathode
bias resistor.