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Voltage Dual Tetrode ·Tetrode-Tetrode

8408

Quick-heating internally neutralized twin tetrode designed for RF power amplification and frequency multiplication in mobile or fixed equipment to approximately 500 MHz.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
-
Socket code
-
Base pins
9
Nominal heater
11 V / 3.1 A

Description

The Telefunken 8408 is a quick-heating, internally neutralized twin tetrode for RF power amplification and frequency multiplication in mobile or fixed equipment.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
9
Nominal heater voltage
11 V
Nominal heater current
3.1 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

2 physical sections, each with unique specifications.

Section 1

Tetrode

X-ray radiationInterelectrode capacitances
Transconductance
0.007 S
Amplification factor
26
Max plate voltage
300 V
Max screen voltage
200 V
Max plate dissipation
4 W
Max screen dissipation
2.5 W
Max cathode current
45 mA

Representative row for two electrically identical tetrode sections.

Section 2

Tetrode

X-ray radiationInterelectrode capacitances
Transconductance
0.007 S
Amplification factor
26
Max plate voltage
300 V
Max screen voltage
200 V
Max plate dissipation
4 W
Max screen dissipation
2.5 W
Max cathode current
45 mA

Second physical tetrode section; electrically identical twin section.

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

1959 Telefunken

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Characteristics

  • Heater Voltage

    11 V

  • Heater Current

    3.1 A

  • Heater Warmup Time

    0.5 s

    Maximum

  • Maximum Intended Frequency

    500 MHz

  • Transconductance

    7000 uS

    Each section