Western electric 247 a brochure

Page 1

BELL SYSTEM PRACTICES K SECTION AB46.247A
TRANSMISSION ENGINEERING AND DATA ISSUE I, APRIL 1948
ELECTRON TUBE DATA A.T.&T. CO. STANDARD

TRIODE ,
AUDIO-FREQUENCY AMPLIFIER Wfifefli £166 10

DESCRIPTION

. The 247A is a low power triode having an indirectly heated cathode. It is designed for
use in audio-frequency amplifier, oscillator, and detector circuits.

CHARACTERISTICS

Heater Voltage , , , , . . . I . I . . . . 2.0 volts
Maximum Plate Voltage , . . . . . . . . . . 180 volts
. Amplification Factor . l l l . . 15

ELECTRON TUBE DATA SHEET
FIL4E: GENERAL PURPOSE SECTION
11- 7

Page 2

247A - PAGE 2

GENERAL CHARACTERISTICS

ELECTRICAL DATA

Heater Voltage, A-C or D-C

Heater Current

Direct Interelectrode Capacitances (without external shield)
Grid to Plate
Input
Output

MECHANICAL DATA
Cathode

Bulb

Base

Mounting Position

Dimensions and pin connections shown in outline drawing on Page 4

MAXIMUM RATINGS, Design-Cenler Values

Plate Voltage

Plate Dissipation

Plate Current
Heater-Cathode Voltage

2.0 volts

1.6 amperes

3.1 uuf
2.9 uuf
2.2 uuf

Coated Unipotential
ST 14
Medium S-pin
Any

180 volts
2.0 watts

10.0 milliamperes

100 volts

TYPICAL OPERATING CONDITIONS AND CHARACTERISTICS-CLASS A1 AMPLIFIER

Plate Voltage . . . 120
Grid Voltage . -6.0
Peak A-F Grid Voltage 6.0
Plate Current 1.3
Transconductance 600
Amplification Factor 14.2
Plate Resistance 23500
Load Resistance 120000
Maximum Signal Power Output 22
Total Harmonic Distortion 4.5

HEATER VOLTAGE = 2 0 VOLTS

(II 0

is

PLATE CURRENT IN MILLIAMPERES
b)

N

-14 -13 -12 -11 -10 -9 -B -7 -6
GRID VOLTAGE

135
-4.5
4.5
3.2
940
15.2
16000
80000
21

2

150
-6

6

2.8
850
14.8
17400
87000
32

2.5

180 volts
-7 volts
7 volts

3.6 milliamperes

940 micromhos
14.9

15700 ohms
78500 ohms

49 milliwatts
3 percent

+1