TT20

Dual common-cathode RF tetrode for UHF power amplification and multiplication service. Marconi data supports push-pull Class C operation into the several-hundred-megahertz region, including frequency-tripler use in professional communications transmitters.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: -
Socket code: -
Base pins: -
Nominal heater: 12.6 V / 650 mA

Description

The TT20 is a dual tetrode with two systems around a common cathode, designed for UHF amplifier service up to about 600 MHz.

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: 12.6 V
Nominal heater current: 650 mA
Parallel heater voltage: 6.3 V
Parallel heater current: 1.3 A
Series capable: Yes

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: 0.0025 S
Max plate voltage: 600 V
Max screen voltage: 250 V
Max plate dissipation: 10 W
Max screen dissipation: 1.5 W
Max grid dissipation: 0.5 W

Representative section row for two equivalent systems. Published maximum ratings and characteristics audited; remaining useful numerical data retained in parameter table.

Section 2

Tetrode

X-ray radiationInterelectrode capacitances

Transconductance: 0.0025 S
Max plate voltage: 600 V
Max screen voltage: 250 V
Max plate dissipation: 10 W
Max screen dissipation: 1.5 W

Second physical tetrode system sharing the common cathode.

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

1955 Marconi

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Other

Frequency. At frequencies above
150 MHz
Frequency. At frequencies above 150 Mc/s, with only ZDIAT-l‘ ﬂ IB1M7AX
the anode voltage: e.g. Va=> [1]
500 MHz
the anode voltage: e.g. Va=>500 V at f=200 Mc/s and
the anode voltage: e.g. Va=> [2]
200 MHz
the anode voltage: e.g. Va=>500 V at f=200 Mc/s and
Va== [1]
300 MHz
Va==300V at f=430 Mc/s. When the frequency
Va== [2]
430 MHz
Va==300V at f=430 Mc/s. When the frequency
(
1 W
(1) RFPOWER AMPLIFIER - CLASS C
v‘\; (
3
v‘\; (3) FREQUENCY TREBLER
(
2 W
(2) RF POWER AMPLIFIER - CLASS C
Anode current for each section plotted against anode voltage for screen-grid voltage of
250 V
Anode current for each section plotted against anode voltage for screen-grid voltage of 250v.
Anode current for each section plotted against anode voltage with screen-grid voltage of
200 V
Anode current for each section plotted against anode voltage with screen-grid voltage of 200v.
Published value [1]
3001
3001 30 moSNNREN =L TTT natural cooling)
Published value [2]
30
3001 30 moSNNREN =L TTT natural cooling)
Frequency characteristic for “Class C”' push-pull telegraphy showing anode efficiency and output power with V,==
400 W
Frequency characteristic for “Class C”' push-pull telegraphy showing anode efficiency and output power with V,==400v.
Heater voltage series
12.6 V
Published series heater connection.
Heater current series
650 mA
Published series heater current.
Heater voltage parallel
6.3 V
Published parallel heater connection.
Heater current parallel
1.3 A
Published parallel heater current.