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812A

Medium-mu directly heated power triode for RF amplification, oscillation, and modulation. Approximately 65 W plate dissipation and kilovolt-class operation provide a useful balance of gain, drive requirements, and transmitting power.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 3G
Socket code: UX4
Base pins: 4
Nominal heater: 6.3 V / 4 A

Description

Power triode for RF amplifier, modulator and oscillator service.

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: 3G
Socket code: UX4
Base pins: 4
Nominal heater voltage: 6.3 V
Nominal heater current: 4 A
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

3G - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1Pin 1	—	F — Filament Transcribed directly from EIA chart; independent cross-check not yet performed.	Unverified EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3G
PIN3Pin 3	A	G1 — Control Grid Transcribed directly from EIA chart; independent cross-check not yet performed.	Unverified EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3G
PIN4Pin 4	—	F — Filament Transcribed directly from EIA chart; independent cross-check not yet performed.	Unverified EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3G
CAP1Top cap	A	P — Plate (Anode) Transcribed directly from EIA chart; independent cross-check not yet performed.	Unverified EIA Base Connections chart, page 127 (uploaded BaseCodeDataCharts_OCR), base 3G

Section ratings

1 physical section, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Amplification factor: 29
Max plate voltage: 1500 V
Max plate dissipation: 65 W
Max grid dissipation: 7 W
Max cathode current: 175 mA

Published ratings/characteristics promoted where unambiguous.

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

1950 General Electric Transmitting Types

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

HeaterOrFilamentVoltage
6.3 V
HeaterOrFilamentCurrent
4 A

Other

FrequencyForMaximumRatings
30 MHz

Data set 02

1956 RCA Transmitting Tubes

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Amplification Factor
29

Other

Maximum Plate Voltage
1500 V
Maximum Plate Dissipation
65 W
Maximum Cathode Current
175 mA
Full-Input Operating Frequency Maximum
30 MHz
Power Output
135 W
ClassC,RF
Typical Plate Voltage
1125 V
Representative published point
Typical Plate Current
125 mA
Representative published point

Data set 03

1963 Amperex Condensed

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
1250 V
RFPower
Plate current
140 mA
RFPower
Power output
130 W
RFPower
Grid voltage
-90 V
RFPower
Grid current
30 mA
RFPower
Maximum frequency
100 MHz
RFPower

Data set 04

1971 RCA HB3 Binder 6 of 7

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Heater/filament voltage nominal
6.3 V
WholeTube
Heater/filament current nominal
4 A
WholeTube
Grid to filament
5.4 pF
Published source row
Plate to filament
0.77 pF
Published source row

Other

Voltage (AC or DC)
6.3 V
Published source row
Voltage (AC or DC) (value 2)
0.3 V
Published source row
Current at filament volts
6.3 V
Published source row
Current at filament volts (value 2)
4 V
Published source row
DC PLATE VOLTAGE
1250 V
Published source row
DC PLATE VOLTAGE (value 2)
1500 V
Published source row
MAX.-SIGNAL DC PLATE CURRENT'
175 mA
Published source row
MAX.-SIGNAL DC PLATE CURRENT' (value 2)
175 mA
Published source row
MAX.-SIGNAL PLATE INPUT`
165 W
Published source row
MAX.-SIGNAL PLATE INPUT` (value 2)
235 W
Published source row
PLATE DISSIPATION'
45 W
Published source row
PLATE DISSIPATION' (value 2)
65 W
Published source row
DC Plate Voltage
1250 V
Published source row
DC Plate Voltage (value 2)
1500 V
Published source row
DC Grid Voltage#
-40 V
Published source row
DC Grid Voltage# (value 2)
-48 V
Published source row
Peak AF Grid-to-Grid Voltage
225 V
Published source row
Peak AF Grid-to-Grid Voltage (value 2)
270 V
Published source row
Zero-Signal DC Plate Current
22 mA
Published source row
Zero-Signal DC Plate Current (value 2)
28 mA
Published source row
Max.-Signal DC Plate Current
260 mA
Published source row
Max.-Signal DC Plate Current (value 2)
310 mA
Published source row
DC PLATE VOLTAGE
1000 V
Published source row
DC PLATE VOLTAGE (value 2)
1250 V
Published source row
DC GRID VOLTAGE
-200 V
Published source row
DC GRID VOLTAGE (value 2)
-200 V
Published source row
DC PLATE CURRENT
125 mA
Published source row
DC PLATE CURRENT (value 2)
150 mA
Published source row
DC GRID CURRENT
35 mA
Published source row
DC GRID CURRENT (value 2)
35 mA
Published source row
PLATE INPUT
115 W
Published source row
PLATE INPUT (value 2)
175 W
Published source row
PLATE DISSIPATION
30 W
Published source row
PLATE DISSIPATION (value 2)
45 W
Published source row
DC Plate Voltage
1000 V
Published source row
DC Plate Voltage (value 2)
1250 V
Published source row
DC Grid Voltage
3400 ohm
Published source row
DC Grid Voltage (value 2)
3300 ohm
Published source row
Peak RF Grid Voltage
220 V
Published source row
Peak RF Grid Voltage (value 2)
240 V
Published source row
DC Plate Current
115 mA
Published source row
DC Plate Current (value 2)
140 mA
Published source row
DC Grid Current (Approx.)
33 mA
Published source row
DC Grid Current (Approx.) (value 2)
35 mA
Published source row
Power Output (Approx )
85 W
Published source row
Power Output (Approx ) (value 2)
130 W
Published source row
DC PLATE VOLTAGE
1250 V
Published source row
DC PLATE VOLTAGE (value 2)
1500 V
Published source row

Data set 05

199X Svetlana

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

T he SvetlanaTM
812 A
SourcePage1-2
the plate cap. The Svetlana
812 A
SourcePage1-2
modulator or RF amplifier at full ratings to
30 MHz
SourcePage1-2
The Svetlana
812 A
SourcePage1-2
Voltage (AC or DC) 6.3 ±
0.3 V
SourcePage1-2
Current
4 A
SourcePage1-2
Maximum frequency for full ratings
30 MHz
SourcePage1-2
Grid to filament
5.4 pF
SourcePage1-2
Plate to filament
0.77 pF
SourcePage1-2
Grid to plate
5.5 pF
SourcePage1-2

Other

DC plate voltage 1250
1500 V
SourcePage1-2
Maximum-signal DC plate current 175
175 mA
SourcePage1-2
Plate Dissipation 45
65 W
SourcePage1-2
Grid Dissipation 7
7 W
SourcePage1-2
DC grid voltage -200
-200 V
SourcePage1-2
Typical Operation, Class C (Frequencies to
30 MHz
TypicalOperation
DC plate voltage 1250
1500 V
TypicalOperation
DC grid voltage -90
-120 V
TypicalOperation
Peak grid voltage 200
240 V
TypicalOperation
Plate current 140
170 mA
TypicalOperation
DC grid current 30
30 mA
TypicalOperation
Grid drive power* 5.4
6.5 W
TypicalOperation
Power output * 130
190 W
TypicalOperation
Plate dissipation 45
65 W
TypicalOperation
DC grid voltage -40
-48 V
TypicalOperation
Peak grid voltage 225
270 V
TypicalOperation
Plate current 260
310 mA
TypicalOperation
Zero signal plate current 22
28 mA
TypicalOperation
Grid driving power* 3.5
5 W
TypicalOperation
Power output * 235
340 W
TypicalOperation
Effective load resistance 12,200
13200 ohms
TypicalOperation