Western electric 347 a brochure

Page 1

BELI. SYSTEM PRACTICES SECTION AB46.347A
TRANSMISSION ENGINEERING AND DATA ISSUE I, AUGUST 1943
ELECTRON TUBE DATA A.T.&T. CO. STANDARD

TRIODE
AUDIO-FREQUENCY AMPLIFIER Western Electric

DESCRIPTION

The 347A is a triode designed for use as an audio-frequency amplifier where exception-
. ally low tube noise is required. Special design features minimize both the microphonic

noise and the hum produced by a.c. operation of the heater.

CHARACTERISTICS

Heater Voltage . . V . . , . . . . . . 6.3 volts

Maximum Plate Voltage . , , . a a l l l , 180 volts
. Amplification Factor . V . . . . . . . . i . . . 15

ELECTRON TUBE DATA SHEET
FILE: GENERAL PURPOSE SECTION

11-47

Page 2

347A - 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 5

MAXIMUM RATINGS, Design-Center Values

Plate Voltage

Plate Dissipation

Plate Current
Heater-Cathode Voltage

TYPICAL OPERATING CONDITIONS AND CHARACTERISTICS-CLASS A1 AMPLIFIER

Plate Voltage 120
Grid Voltage -6.0
Peak A-F Grid Voltage 6.0
Plate Current . 1.0
Transconductance 560
Amplification Factor 14.8
Plate Resistance 26600
Load Resistance 100000
Maximum Signal Power Output 24
Total Harmonic Distortion 4
HUM

Under typical operating conditions, and
with the cathode of the tube connected to
the mid-point of the heater circuit, the
equivalent hum voltage in the grid circuit
will be less than 12 microvolts at the supply
frequency and less than 6.0 microvolts at

6.5 volts
0.50 ampere
1.9 uuf
2.4 uuf
3.8 uuf
Coated Unipotential
ST 12
Small Shell Octal 5-Pin
Any
180 volts
2.0 watts
10.0 milliamperes
30 volts
135 160 180 volts
-4.5 -6.0 -7.5 volts
4.5 6.0 7.5 vols
3.0 3.0 2.8 milliamperes
890 880 840 micromhos
15.4 15.5 15.3
17300 17700 18300 ohms
100000 100000 100000 ohms
18 31 48 milliwatts
2.5 3 3 percent

double the supply frequency.

If the insulation leakage and capacitance be-
tween the external grid and heater connec-
tions are kept reasonably low, a resistance of
2 megohms may be used in the grid circuit
without materially afiecting the hum level.