Western electric 358 a brochure

Page 1

BELL SYSTEM PRACTICES AB46.358A
Transmission Engineering and Data Issue 1, February 1962
Electron Tube Data A.T.& T.Co. Standard

. ELECTRON TUBE DATA SHEET
WESTERN ELECTRIC 358A ELECTRON TUBE
O

DESCRI PT I ON

The 358A is a two-electrode, inert-gas-filled, cold cathode tube designed to
provide a visual signal for telephone work. When the tube is conducting, a glow will
appear near the surface of the negative electrode. If a d.c. voltage supply is used
the negative polarity should be applied to the upper electrode. The upper electrode

. terminal may be identified by the adjacent circular dot of contrasting color on the
base. When the tube is operating with an alternating voltage a glow will appear on
both electrodes.

CHARACTERISTICS

Anode Breakdown Voltage, Maximum . . . . . . . 85 volts
. Average Cathode Current. . . . . . . . . . . 7.5 10 18 milliamperes

Average Life, (approx. at above currents) . . T 5000 1000 100 hours
. File: Cold Cathode Section

© American Telephone and Telegraph Company 1962 358A

Page 2

358A - PAGE 2

RATINGS, Absolute System (Note 1)

Cathode Currents

Maximum Peak. . . . . . . . . . . . . . . . . . . 55 milliamperes
Maximum Average. . . . . . . . . . . . . . . . . 18 milliamperes
Ambient Temperature Limits . . . . . . . . . . . . . ~55 to +85° centigrade

ELECTRICAL DATA, Throughout Life(Note m

Min. Bogey Max.

Anode Breakdown Voltage- . - - - - ~ - - - - - - - 65 85 volts
Anode Voltage Drop- - ~ - - - - - - - - - - - - - 60 75 volts
Light Output at 15 mAdc~ - - - . . . - . . . . . - 0.6 - lumen

MECHANICAL DATA

Mounting Position . . . . . . . . Any
Dimensions and terminal connections shown in outline drawing on page 3.

APPLICATION DATA

This tube possesses a unique property not common to filamentary type lamps in
that its impedance is essentially infinite for voltages below breakdown. In some
applications this is an advantageous feature since the tube may be used to pass
current at'the higher potentials without placing a conducting path across the line
for signals of lower voltage.

Unlike filamentary type lamps the light output of this tube is proportional to
the current through the tube instead of varying as a power of this current. This
tube is well adapted to furnishing a visual signal from a varying voltage source.

Note 1: In the "Absolute System" the maximum ratings specified are limiting values above which the
serviceability of the device may be impaired from the viewpoint of life and satisfactory
performance. Maximum ratings, as such, do not constitute a set of operating conditions and
all values may not, therefore, be attained simultaneously.

Note 2: when the tube is operating from a direct current supply. the upper electrode shall be used
as the cathode.