Data set 01
1950 General Electric Transmitting Types
Published operating points and test conditions from this source.
SECTION 1
Tetrode
Other
Power output maximum signal
520 W
ClassAB
Power - Tetrode (NOT beam) (over 1000V 100W) ·Tetrode
4D21
Power tetrode for transmitting RF amplifier and oscillator service, capable of full ratings to about 120 MHz and reduced-rating operation substantially higher.
Directly heatedCold cathodeCommon cathodeDissimilar
- Sections
- 1
- Base
- -
- Socket code
- J4
- Base pins
- -
- Nominal heater
- 5 V / 6.5 A
Description
4D21 is a Tetrode device in the supplied Amperex literature. Radiation- and forced-air-cooled power tetrode; supplied table explicitly co-designates 4-125A/4D21.
Socket description
Jumbo 4-contact
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- -
- Socket code
- J4
- Base pins
- -
- Nominal heater voltage
- 5 V
- Nominal heater current
- 6.5 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
- Transconductance
- 0.00245 S
- Amplification factor
- 5.9
- Max plate voltage
- 3000 V
- Max screen voltage
- 600 V
- Max plate dissipation
- 125 W
- Max screen dissipation
- 20 W
- Max grid dissipation
- 5 W
Published source values promoted where applicable; additional values retained as 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 02
1956 RCA Transmitting Tubes
Published operating points and test conditions from this source.
SECTION 1
Tetrode
Other
Maximum full-rating frequency
120 MHz
Reduced-rating frequency
250 MHz
Construction
Cooling method
Forced air
Data set 03
1962 Eimac
Published operating points and test conditions from this source.
SECTION 1
Tetrode
Characteristic
Frequency for Maximum Ratings
120 MHz
Capacitance
Grid-Plate Capacitance
0.05 pF
Average
Input Capacitance
10.8 pF
Average
Output Capacitance
3.1 pF
Average
Data set 04
1963 Amperex Condensed
Published operating points and test conditions from this source.
SECTION 1
Tetrode
Other
Plate voltage
2500 V
RFAmplifierOrOscillator
Plate current
200 mA
RFAmplifierOrOscillator
RF output power
375 W
RFAmplifierOrOscillator
Grid voltage
-150 V
RFAmplifierOrOscillator
Grid current
12 mA
RFAmplifierOrOscillator
Screen voltage
350 V
RFAmplifierOrOscillator
Maximum frequency at full input rating
120 MHz
Capacitance
Grid-to-plate capacitance
0.05 pF
Grid-to-filament/cathode capacitance
10.8 pF
Plate-to-filament/cathode capacitance
3.1 pF