Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Power - Tetrode (NOT beam) (over 1000V 100W) ·Tetrode

GL8500

Forced-air-cooled metal-ceramic RF power tetrode for grounded-grid Class-B linear and Class-C amplifier or oscillator service to approximately 1250 MHz or higher.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
-
Base pins
-
Nominal heater
6.3 V / 3.8 A

Description

Forced-air-cooled metal-ceramic RF power tetrode for grounded-grid Class-B linear and Class-C amplifier/oscillator service to about 1250 MHz or higher.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
-
Nominal heater voltage
6.3 V
Nominal heater current
3.8 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

Tetrode

X-ray radiationInterelectrode capacitances
Amplification factor
45
Max plate voltage
1250 V
Max screen voltage
250 V
Max plate dissipation
500 W
Max grid dissipation
2 W
Max cathode current
1.75 A

Promoted fields mapped from printed ratings/characteristics headings; specialized published data retained in parameter rows.

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

1964 RMA EIA

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Characteristics

  • Heater voltage bogey

    6.3 V

  • Heater current

    3.8 A

  • Maximum useful frequency

    1250 MHz

Other

  • Heater voltage maximum

    6.8 V

  • Heater voltage minimum at UHF

    5.5 V

  • Cathode heating time minimum

    1 min

  • Peak cathode current maximum

    1.75 A

  • Plate dissipation maximum

    500 W

  • Ceramic temperature maximum

    200 C

  • Anode-seal temperature maximum

    250 C

  • Class-B plate voltage maximum

    2000 V

    ClassB

  • Class-B screen voltage maximum

    320 V

    ClassB

  • Class-B plate current maximum

    250 mA

    ClassB

  • Class-B plate input maximum

    500 W

    ClassB

  • Class-B screen input maximum

    5 W

    ClassB

  • Class-B typical frequency range

    225 to 400 MHz

    ClassB

  • Class-B plate voltage

    1750 V

    ClassB

  • Class-B screen voltage

    250 V

    ClassB

  • Class-B control-grid voltage

    -20 V

    ClassB

  • Class-B peak RF plate voltage

    1250 V

    ClassB

  • Class-B peak RF control-grid voltage

    40 V

    ClassB

  • Class-B plate current

    200 mA

    ClassB

  • Class-B zero-signal plate current

    20 mA

    ClassB

  • Class-B screen current

    5 mA

    ClassB

  • Class-B control-grid current

    10 mA

    ClassB

  • Class-B driving power

    5 W

    ClassB

  • Class-B RF output power

    110 W

    ClassB

  • Class-C maximum plate voltage at 900 MHz

    1600 V

    ClassC

  • Class-C maximum plate voltage at 400 MHz

    2000 V

    ClassC

  • Class-C maximum screen voltage

    320 V

    ClassC

  • Class-C maximum control-grid voltage

    -100 V

    ClassC

  • Class-C maximum plate current

    300 mA

    ClassC

  • Class-C maximum control-grid current

    50 mA

    ClassC

  • Class-C plate input maximum at 900 MHz

    480 W

    ClassC

  • Class-C plate input maximum at 400 MHz

    600 W

    ClassC

  • Class-C screen input maximum

    15 W

    ClassC

  • Class-C typical plate voltage at 900 MHz

    1500 V

    ClassC

  • Class-C typical screen voltage at 900 MHz

    210 V

    ClassC

  • Class-C typical control-grid voltage at 900 MHz

    -40 V

    ClassC

  • Class-C typical plate current at 900 MHz

    300 mA

    ClassC

  • Class-C typical screen current at 900 MHz

    10 mA

    ClassC

  • Class-C typical control-grid current at 900 MHz

    20 mA

    ClassC

  • Class-C typical driving power at 900 MHz

    14 W

    ClassC

  • Class-C typical output power at 900 MHz

    205 W

    ClassC

  • Class-C typical plate voltage at 400 MHz

    2000 V

    ClassC

  • Class-C typical screen voltage at 400 MHz

    225 V

    ClassC

  • Class-C typical plate current at 400 MHz

    250 mA

    ClassC

  • Class-C typical driving power at 400 MHz

    15 W

    ClassC

  • Class-C typical output power at 400 MHz

    300 W

    ClassC

Capacitance

  • Cathode-to-plate capacitance

    0.006 pF

  • Input capacitance with control grid tied to screen

    19.5 pF

  • Output capacitance with control grid tied to screen

    6.4 pF

Construction

  • Cooling method

    Forced air

Application

  • Application

    RF power amplifier / oscillator / communications final or driver

Data set 02

1968 General Electric Co

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Other

  • G; to G, E,=

    1000 V

    G; to G, E,=1000V comlantg Air Tlc;n:

  • =

    275 V

    . =275V DC; perature, mini- )

  • 2—4-;' 1 ANODE HUB TEMPERATURE !

    1301 A

    2—4-;' 1 ANODE HUB TEMPERATURE ! 1301A. ——]

  • Diameter A

    0.03 in

    Diameter A 0,030 inches

  • Diameter B

    0.016 in

    Diameter B 0,016 inches when inserted over the cathode and filament terminal,

  • Diameter C

    0.036 in

    Diameter C 0,036 inches gage #2 shall contact the tube REFERENCE SURFACE

  • Diameter D

    0.042 in

    Diameter D 0,042 inches

  • ment terminal diameter (C)

    0.016 in

    ment terminal diameter (C) - 0,016 inches,

Capacitance

  • Capacitances proximate........ 0.9 0.5

    0.2 in

    Capacitances proximate........ 0.9 0.5 0.2 Inches-