Western electric 393 a brochure

Page 1

BELL SYSTEM PRACTICES SECTION A346. 393A
Transmission Engineering and Data Issue 2, October 1962

Electron Tube Data A.T.& T. Co. Standard

ELECTRON TUBE DATA SHEET
WESTERN ELECTRIC 393A ELECTRON TUBE

DESCRIPTION

The 393A is We-slectr mercury-vapor and gas-filled thyratron with a
negative co-{ teristic. This tube is designed for use in regulated

............. 1250 volts
Average Cathode Current ................ 1.5 amperes

FILE: THYRATRON SECTION

@ American Telephone and Telegraph Company 1962

393A

ll

Page 2

393A - Page 2

E 5T WGS ha a Va ues
Peak Anode Voltaee
Inverse . . . . . . . . . . . . . . . . . . . . . . 1250 volts
Forward . . . . . . . . . . . . . . . . . . . . . . 1250 volts
Cathode Current
Peak. . . . . . . . . . . . . . . . . 6 amperes
Average . . . . . . . . . . 1.5 amperes
Surge (maximum duration 0. l second) . . . . . . . . 120 amperes
Averagine Time. . . . . . . . . . . . . . . . . . . 5 seconds
Negative Grid Voltane
Before Conduction . . . . . . . . . . . . . . . . . 500 volts
During Conduction . . . . . . . . . . . . . . . . . 10 volts
Positive Grid Current, Average
(averaging tine - one cycle). . . . . . . . . . . . .010 ampere

Condensed Kercury Temperature Limits . . . . . . . . . -55 to +80 centigrade

EIECTRICAL DiTl

Ein. Bogey flax.

Filament Voltage . . . . . . . . . . . . . . . . . 2.37 2.5 3732 volts
Filament Current at 2.5 Volts. . . . . . . . . . . --- 7.0 7.75 amperes
Filament Heating Time Required . . . . . . . . . . l5 --- --- seconds
Anode to Grid Capacitance. . . . . . . . . . . . . -- 1.8 --- uuf
Grid to Filament Capacitance . . . . . . . . . . . ~-- 5.0 --- uuf

Jeionization Time, Approximate2
Ebb-1250 voltszTHe-PCC:Ib-6 anperes;

E c--18 volts: Rg-ZC.CGO ohms. . . . . . . . . . --- 1200 --- microseconds
Ionization Tine, Approximate3

Ebb-100 voltazTHz-LOG:grid overvoltege-5 volts . --- 35 --- microseconds

Ebb-100 volts:THg-808:grii ovarvoltaga-25 volts. --- 0.5 --- microseconds
Anode Voltage Drop . . . . . . . . . . . . . . . . --- 15 --- volts
Critical Grid Current at 220 Anode Volts . . . . . --- --- 5 microamperes
Change in Critical Grid Voltaee at

500 Anode Volts from +20 to +90Tflg . . . . . . --- 0.2 --- volt

JATL

Type of Cooling. . . . . . . . . . . . . . . . . . Convection
Equilibriun Condensed Lercury Temperature

Rise lbove Ambient,1pproximate
at Full Load. . . . . . . . . . . . . . . . . . . . . . 30 centierade
it No Load. . . . . . . . . . . . . . . . . . . . . . . 20 centierade
hounting Position. . . . . . . . . . . . . . . . . . . . . Vertical-base down
Ne t Weight, prroximate. . . . . . . . . . 3 ounces

Dimensions and pin connections shown in outline drawing on Pane L.

1

For startin? conditions only. Equilibrium operation is limited to +20°
minimum condensed mercury temperature.

Deicnization tine decreases with an increase in negative grid voltage or
with a iecreise in (a) condensed mercury temperature (Tflg), (b) grid resis-
tance or (c) anoie current immediately preceding the end of conduction.
Ionization tine decreases With an increase in (a) anode voltage, (b) con-
densed mercury temperature (THg) or (0) grid overvoltafi . Grid overvcltage

is defined as the magnitude by which the applied voltage exceeds, in a
peeitive direction, the critical arid voltage value. Critical grid voltage

is the instantaneous value of grid voltage at the time when anode current
starts to flow.