8874

Forced-air-cooled ceramic-metal power triode for Class A, B, and C RF amplifier service. Rated for 400 W plate dissipation, with full ratings to roughly 500 MHz and about 587 W published Class AB2 output.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: E11-81
Socket code: E11
Base pins: 11
Nominal heater: 6.3 V / 3 A

Description

The Eimac 8874 is a compact external-anode ceramic-metal triode for class-AB or class-C radio-frequency amplifiers, designed for forced-air cooling.

Socket description

Large-wafer Elevenar 11-pin with ring

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: E11-81
Socket code: E11
Base pins: 11
Nominal heater voltage: 6.3 V
Nominal heater current: 3 A
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

E11-81 - 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

Transconductance: 0.029 S
Max plate voltage: 2200 V
Max plate dissipation: 400 W
Max grid dissipation: 5 W
Max cathode current: 350 A

Promoted values are taken from printed General Characteristics / Maximum Ratings. Additional published conditions and operating data are preserved in parameters.

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

1962 Eimac

Published operating points and test conditions from this source.

SECTION 1

Triode

Capacitance

Input Capacitance
20.5 pF
CathodeGrounded
Output Capacitance
0.03 pF
CathodeGrounded
Grid-Plate Capacitance
6 pF
CathodeGrounded

Other

Frequency Maximum
500 MHz
Maximum DC Plate Current
350 mA
Typical Plate Voltage
2000 V
ClassAB2
Typical Useful Output Power
587 W
ClassAB2;Frequency=30MHz

Data set 02

199X Svetlana

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

Heater voltage (AC or DC) 6.3 ±
0.3 V
service. The principal use is as an RF amplifier, in Class A, B or C
Heater current @
6.3 V
service. The principal use is as an RF amplifier, in Class A, B or C
Maximum frequency at full ratings
500 MHz
service. The principal use is as an RF amplifier, in Class A, B or C
Input
20.5 pF
service. The principal use is as an RF amplifier, in Class A, B or C
Output
0.03 pF
service. The principal use is as an RF amplifier, in Class A, B or C
Grid-Plate
6 pF
service. The principal use is as an RF amplifier, in Class A, B or C
Input
20.5 pF
service. The principal use is as an RF amplifier, in Class A, B or C
Output
6 pF
service. The principal use is as an RF amplifier, in Class A, B or C

Other

Maximum-signal DC plate current
350 mA
Maximum ratings Dimensional Data
Plate Dissipation
400 W
Maximum ratings Dimensional Data
Grid Dissipation
5 W
Maximum ratings Dimensional Data
Peak RF grid-cathode voltage 67 50
67 V
Typical Operation, Class AB2 Cathode Driven
Two tone plate current 312 245
300 mA
Typical Operation, Class AB2 Cathode Driven
Zero signal plate current 22 10
22 mA
Typical Operation, Class AB2 Cathode Driven
Two tone grid current 12 10
39 mA
Typical Operation, Class AB2 Cathode Driven
Peak RF drivng power 26 18
27 W
Typical Operation, Class AB2 Cathode Driven
Power output (approx.) 587 526
505 W
Typical Operation, Class AB2 Cathode Driven