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838

High-mu zero-bias power triode for Class B audio amplification and RF oscillator or power-amplifier service. Its high amplification factor, roughly 100 W plate dissipation, and kilovolt operation provide strong gain in audio and transmitting stages.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: UX4
Base pins: 4
Nominal heater: 10 V / 3.25 A

Description

Zero-bias Class-B AF power amplifier and RF oscillator/power-amplifier triode.

Socket description

Medium-shell UX 4-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: UX4
Base pins: 4
Nominal heater voltage: 10 V
Nominal heater current: 3.25 A
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 12500 Ω
Transconductance: 0.008 S
Amplification factor: 100
Max plate voltage: 1250 V
Max plate dissipation: 100 W
Max cathode current: 175 mA

Maximum ratings and characteristic constants promoted where reliably published in the approved sheet.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1938 RCA Transmitting Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

megacycles. The maximum plate dissipation of the RCA-838 is
100 W
megacycles. The maximum plate dissipation of the RCA-838 is 100 watts for
D-C Plate Voltage
1250 V
D-C Plate Voltage -- 1250 max. Volts
D-C Plate Voltage. 1000
1250 V
D-C Plate Voltage. 1000 1250 Volts
D-C Plate Voltage
1250 V
D-C Plate Voltage .. 1250 max. Volts
Plate Dissipation
100 W
Plate Dissipation . 100 max. Watts
D-C Plate Voltage ... . 1000
1250 V
D-C Plate Voltage ... . 1000 1250 Volts
Peak R-F Grid Voltage .-. . 70
60 V
Peak R-F Grid Voltage .-. . 70 60 Volts
D-C Grid Current (Approx.) .. ... 15
15 mA
D-C Grid Current (Approx.) .. ... 15 15 Milliamperes
D-C Plate Voltage
1000 V
D-C Plate Voltage ... 1000 max. Volts
D-C Plate Current
175 mA
D-C Plate Current.-. 175 max. Milliamperes
Plate Dissipation
67 W
Plate Dissipation ... 67 max. Watts
D-C Plate Voltage . 750
1000 V
D-C Plate Voltage . 750 1000 Volts
Peak R-F Grid Voltage .. 220
255 V
Peak R-F Grid Voltage .. 220 255 Volts
D-C Plate Current .. 150
150 mA
D-C Plate Current .. 150 150 Milliamperes
Grid Resistor .. 1670
2250 Ω
Grid Resistor .. 1670 2250 Ohms
Driving Power (Approx.) . 14
16 W
Driving Power (Approx.) . 14 16 Watts
Power Output (Approx.) . 65
100 W
Power Output (Approx.) . 65 100 Watts
D-C Plate Voltage
1250 V
D-C Plate Voltage 1250 max. Volts
D-C Grid Voltage
-400 V
D-C Grid Voltage ..... -400 max. Volts
D-C Plate Current
175 mA
D-C Plate Current 175 max. Milliamperes
D-C Grid Current
70 mA
D-C Grid Current . 70 max. Milliamperes
Plate Input
220 W
Plate Input .. 220 max. Watts
Plate Dissipation
100 W
Plate Dissipation ..... 100 max. Watts
D-C Plate Voltage --- 750 1000
1250 V
D-C Plate Voltage --- 750 1000 1250 Volts
Peak R-F Grid Voltage . 190 195
200 V
Peak R-F Grid Voltage . 190 195 200 Volts
D-C Plate Current .. 150 150
150 mA
D-C Plate Current .. 150 150 150 Milliamperes
D-C Grid Current (Approx.) . 30 30
30 mA
D-C Grid Current (Approx.) . 30 30 30 Milliamperes
Grid Resistor ... 2670 2835
3000 Ω
Grid Resistor ... 2670 2835 3000 Ohms
Driving Power (Approx.) --- 6 6
6 W
Driving Power (Approx.) --- 6 6 6 Watts
Power Output (Approx.) - 65 100
130 W
Power Output (Approx.) - 65 100 130 Watts
voltage of
1250 V
voltage of 1250 volts, the exceptions are: grid-bias volt¬
For high-frequency operation above
30 MHz
For high-frequency operation above 30 megacycles,

Data set 02

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

This feature facilitates the design of class
8 A
This feature facilitates the design of class 8 amplifiers to give high output
ble of giving an output of
838 W
ble of giving an output of 260 watts with less than 5% distortion. The 838 may
ings for frequencies as high as
8 MHz
ings for frequencies as high as 30 Mc. The maximum plate dissipation for class 8
and class C telegraph services is
100 W
and class C telegraph services is 100 watts.
FILAMENT VOLTAGE (A.C. or D.C.)
10 V
FILAMENT VOLTAGE (A.C. or D.C.) 10.0 volts
FtLAMENT CURRENT
3.25 A
FtLAMENT CURRENT 3.25 Amperes
D—C PLATE VOLTAGE
1250 V
D—C PLATE VOLTAGE 1250 max. Volts
MAX.~SIGNAL D~C PLATE CURRENT¥
175 mA
MAX.~SIGNAL D~C PLATE CURRENT¥ 175 max. Milliamperes
MAX.~SIGNAL PLATE INPUT*
220 W
MAX.~SIGNAL PLATE INPUT* 220 max. watts
PLATE DISSIPATION*
100 W
PLATE DISSIPATION* 100 max. Watts
D-C Plate Voltage
1250 V
D-C Plate Voltage 1000 1250 Volts
0-C Grid voltage 00 [ [ volts
0 V
0-C Grid voltage 00 [ [ volts
Peak A-F Grid-to-Grid voltage
200 V
Peak A-F Grid-to-Grid voltage 200 200 volts
Zero-Sig. D-C Plate Current
148 mA
Zero-Sig. D-C Plate Current 106 148 Milliamperes
Max.-Sig. D-C Plate Current
320 mA
Max.-Sig. D-C Plate Current 320 320 Milliamperes
Max,~Sig. Driving Power (Approx
7.5 W
Max,~Sig. Driving Power (Approx 7 7.5 watts
Max.-Sig. Power Output (Approx.) #
260 W
Max.-Sig. Power Output (Approx.) # 200 260 watts
0-C PLATE VOLTAGE 1250 max. Volts
1250 V
0-C PLATE VOLTAGE 1250 max. Volts
D-C PLATE CURRENT
150 mA
D-C PLATE CURRENT 150 max. Milliamperes
PLATE {NPUT
150 W
PLATE {NPUT 150 max. Watts
PLATE DISSIPATION
100 W
PLATE DISSIPATION 100 max. Watts
D—-C Plate voltage
1250 V
D—-C Plate voltage 1000 1250 volts
D-C Grid vVolitage
0 V
D-C Grid vVolitage 00 0 0 Volts
Peak R-F Grid Voltage
60 V
Peak R-F Grid Voltage 70 60 volts
0-C Plate Current 130 106 Milliamperes
106 mA
0-C Plate Current 130 106 Milliamperes
D-C Grid current {Approx,) **
15 mA
D-C Grid current {Approx,) ** 15 15 Milliamperes
Driving Power (Approx,) o
6 W
Driving Power (Approx,) o 8 6 watts
Power Output (Approx.)
42.5 W
Power Output (Approx.) 40 42.5 watts
D-C PLATE VOLTAGE
1000 V
D-C PLATE VOLTAGE 1000 max. Volts
D-C GRID VOLTAGE ~
400 V
D-C GRID VOLTAGE ~400 max. Volts
D-C PLATE CURRENT
175 mA
D-C PLATE CURRENT 175 max. Milliamperes
0-C GRID CURRENT 70 max. Milliamperes
70 mA
0-C GRID CURRENT 70 max. Milliamperes
PLATE (INPUT
175 W
PLATE (INPUT 175 max, watts
PLATE DISSIPATION
67 W
PLATE DISSIPATION 67 max. Watts

Characteristic

Load Resistance {Per tube)
2250 ohm
Load Resistance {Per tube) 1725 2250 ohms
Effective Load Resistance (Plate-to-plate)
9000 ohm
Effective Load Resistance (Plate-to-plate) 6900 9000 Ohms

Data set 03

1945 United Electronics

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Filament voltage
10 V
Filament current
3.25 A
Plate resistance
12500 ohm
Mutual conductance
8000 uS
Amplification factor
100

Other

Maximum direct plate voltage
1250 V
Maximum plate dissipation
100 W
Maximum direct plate current
175 mA

Data set 04

1950 General Electric Transmitting Types

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

HeaterOrFilamentVoltage
10 V
HeaterOrFilamentCurrent
3.25 A

Other

FrequencyForMaximumRatings
30 MHz

Data set 05

1956 RCA Transmitting Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

HeaterOrFilamentVoltage
10 V
HeaterOrFilamentCurrent
3.25 A

Other

MaximumOperatingFrequency
120 MHz
Reduced ratings may apply at upper frequencies

Data set 06

1958 Amperex Industrial

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
1250 V
RFPowerAmplifier;ClassC
Plate current
160 mA
RFPowerAmplifier;ClassC
Power output
150 W
RFPowerAmplifier;ClassC
Control-grid voltage
-150 V
RFPowerAmplifier;ClassC
Grid current
26 mA
RFPowerAmplifier;ClassC
Maximum frequency at full input
30 MHz
RFPowerAmplifier

Capacitance

Grid-to-plate capacitance
8 pF
Section1
Grid-to-filament capacitance
6.5 pF
Section1
Plate-to-filament capacitance
3 pF
Section1

Data set 07

1963 Amperex Condensed

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
1250 V
RFPowerAmplifier
Plate current
175 mA
RFPowerAmplifier
Power output
130 W
RFPowerAmplifier
Control-grid voltage
-90 V
RFPowerAmplifier
Grid current
30 mA
RFPowerAmplifier
Maximum frequency at full input
30 MHz
RFPowerAmplifier

Capacitance

Grid-to-plate capacitance
8 pF
Section1
Grid-to-filament capacitance
6.5 pF
Section1
Plate-to-filament capacitance
3 pF
Section1