This specification specifies the detailed requirements for FU251F transmitting tubes. This specification applies to FU251F transmitting tubes. FU251 transmitting tubes are mainly used for AB1 audio amplification and power input of single-sideband communication machines below 500MHz. They can also be used for amplification in other ultra-short wave radio equipment. SJ 20022-1992 Detailed Specifications for FU251F Transmitting Tubes SJ20022-1992 Standard Download Decompression Password: www.bzxz.net
This specification specifies the detailed requirements for FU251F transmitting tubes. This specification applies to FU251F transmitting tubes. FU251 transmitting tubes are mainly used for AB1 audio amplification and power input of single-sideband communication machines below 500MHz. They can also be used for amplification in other ultra-short wave radio equipment.

1 Scope
People's Republic of China Electronic Industry Military Standard Electronic Tube
Detail specification for transmitting tube of type FU251F
Detail specification for transmitting tube of type FU251F1.1 Subject content
This specification specifies the detailed requirements for FU251F transmitting tube. 1.2 Scope of application
This specification applies to FU251F transmitting tube. SJ20022—92
FU251F transmitting tube is mainly used for AB, class audio amplification and power amplification in single-sideband communication equipment below 500MHz, and can also be used for amplification in other ultra-short wave radio equipment. 1.3 Structural characteristics
Structure: metal ceramic tetrode;
Installation position: arbitrary;
Cooling method: strong air cooling;
Mass: maximum 150g.
1.4 Dimensions and electrode connections
For dimensions, see Figure A1 in Appendix A (Supplement), and for electrode connections, see Figure A2. 1.5 Absolute ratings (AB, Class or C telegraph) Table 1
Hot wire voltage
Anode DC voltage
Control grid DC voltage
Gate DC voltage
AB, Class
C telegraph
Anode DC current
Control grid power dissipation
Curtain grid power dissipation
Anode power dissipation
Metal-ceramic sealing temperature
Anode heat dissipation Temperature at the root of the sheet
Cathode preheating time
China Electronics Industry Corporation 1992-02-01 Release No.
Minimum value
Maximum value
See d in 6.2
1992-02-01 Implementation
1.6 Test conditions (TC)
Hot wire voltage
Cathode preheating time
Anode DC voltage
Curtain grid DC voltage
Control grid DC negative voltage
Anode DC current
Cooling air volume
1.7 Typical characteristics
Internal amplifier Coefficient
Transconductance (1,=200mA)
Inter-electrode capacitance:
Input capacitance
Output capacitance
Cross-circuit capacitance
Constant current characteristic curve
Reference documents
GB/T3789-91
GB7274-87
GB11486--89
GJB616—88
GJB922--90
GJB921--90
3 Requirements
3.1 Detailed requirements
SJ20022—9 2
Minimum value
Minimum value
See Appendix D (reference)
Test method for transmitting tube electrical performance
Test method for inter-electrode capacitance of electron tube
Nominal value
Nominal value
Test method for current and voltage of filament or hot wire of electron tube Test method for electron tube
General specification for electron tube
General specification for electron tube packaging
Maximum value
Maximum value
m'/min
All requirements for FU251F transmitting tube shall comply with the provisions of this specification and GJB922 General Specification for Electron Tubes. 3.2 Marking
Model: FU251F;
Military mark: J
Manufacture date and serial number;
Manufacturer's trademark.
Quality assurance provisions
Quality consistency inspection
Inspection or test
Visual inspection
Hot wire current
Control gate DC voltage
Window grid current
Control grid reverse current
Current distribution
Pulse emission current term drop
Part 1
4.2 Quality consistency inspection
GB11486
SJ20022-92
Test conditions
Non-working state
GB/T3789.21
GB/T 3789.2
GB/T3789.4
Part 2
U-2000V
Other TC
Ugm100V
U,-U-250V
tw≥4500μs
fep=11±1Hz
1,≤0.5%
Ripple≤0.1%
U regulation
U.-U-250V
t-≥4500 μs
fe=11±1Hz
Ripple≤0.1%
Uk adjustment
Inspection requirements
Minimum value Maximum value Unit
See Appendix B
Inspection or test
Interchangeable dimensions
Inter-electrode capacitance
Leakage between hot wire and cathode
Controlled shed emission current
Screen grid emission current
Output power
4.3 Quality consistency inspection||tt| |Inspection or test
Dimensions to be controlled
GB7274
SJ20022—92
Test conditions
Non-working state
Non-working state
GB/T3789.
GB/T3789.5
GB/T3789.5
GB/T3789.
Part 3
Uh=150V
Un-150V| |tt||Igi=70mA
Anode and screen grid potential suspended,=120s
1g2=80mA
Anode potential suspended
t=120s
Class AB amplifier
f=-30MHz
U,=1500V
-Ugl=65V
U2=400V
Air volume: 0.2m/min
Test conditions||tt| |Non-working state
Non-working state
α=150m/s*
-20~80 times/min
Times: 1000 times
GJB616.1013
Half sine wave
Pulse width: 11±2ms
Anode upward, vertical direction
GJB616.1608
Non-working state
Inspection requirements
Minimum value Maximum value Unit
See figure A1
Inspection requirements
Minimum value Maximum value Unit
See Figure A1
n=3C,=0
ng—3
Inspection or test
Constant damp heat
After collision, dynamic, constant damp heat test, respectively measure and control the gate reverse current
Life test
Output power
Life test
After test:
Inter-electrode insulation
SJ 20022--92
Continued Table 6
Test conditions
a=-50m/s2
f=50Hz
t=30nin
Anode upward, vertical direction
1=40±2℃
Relative humidity (93±)%
GB/T3789.4bZxz.net
OthersTC
AB, Class Amplifier
f-30NHzU1=-65V
1,-250mA.U,=1500V
Ug2-400V
Air volume=0.2m*/min
AB, class amplifier
GB/T3789.5
GB/T3789.
Note: AQL—Qualified quality level;
IL inspection level
P cycle (month),
n sample size;
C—Qualified judgment number;
D—Destructive items.
5 Delivery preparation
f-30MHz.Ue=-65V
I.-250mA.U.1500V
U2=400V
Air volume=0.2m/min
Non-working state, measured with 500V megaohmmeter
First grid connected to negative pole
Second grid connected to positive pole
Second grid connected to negative pole
First grid connected to negative pole
Inspection requirements
Minimum value Maximum value Unit
12n3C,—1
n-3C,-0
n,-2Cf0
n=2|C,=1
5.1 Packaging
5.1.1 Packaging requirements
S.I20022—92
The packaging should comply with the provisions of GJB921 "General Specification for Electronic Tube Packaging". a.
Packing drawing number ××××××.
Product certificate, factory inspection form.
5.1.2 Packaging Marking
The packaging box marking shall comply with GB191 "Packaging Storage and Transportation Pictorial Marking". 5.1.3 Packaging Test
Put the packaged launch tube on the transport vehicle and drive it for 200 km at a speed of 30 km/h on a Class 3 road, or conduct the test on an equivalent bumper.
The launch tube should not have mechanical damage after transportation, and the parameters of the first part of the quality consistency test should comply with the provisions of the detailed specifications.
The launch tube packaging test is carried out during product identification or structural changes, as well as changes in packaging structure and materials. The sampling plan is n=4, C=1.
5.2 Storage
The launch tube should be stored in a dry, ventilated warehouse without the influence of corrosive gases, with an ambient temperature of -5 to +40℃ and a relative humidity of no more than 80%.
5.3 Transportation
The packaged launch tube can be transported by any means. During transportation, it should avoid severe vibration, impact, mechanical shock, direct rain and corrosion.
6 Notes
6.1 Contents of ordering documents
FU251F launch tube;
Detailed specification number:
Manufacturer code or name:
Quantity.
6.2 Precautions for use
When the launch tube is working, the anode and core column should be forced to cool. The cathode preheating time should be no less than 1min.
When the launch tube is stored for more than half a year or the storage warehouse is relatively humid, the cathode preheating time should be no less than 30min. At different working frequencies, the voltage of the hot wire should be adjusted to the specified value: Color
Frequency (MHz)
301~400
401~500
To prevent oxidation of the coating, avoid direct contact of the hands with the transmitting tube. f.
The transmitting tube should be connected to the voltage in the following order and disconnected in the reverse order. Hot wire voltage
Control grid bias
—Anode voltage
Curtain grid voltage
Pulse voltage
SJ20022-92
SJ20022-92
Appendix A
FU251F transmitter tube appearance and pin connection diagram (supplement)
Quality consistency inspection
Minimum size
Quality consistency inspection
Minimum size
FU251F transmitter tube appearance
* 4, 6, 8
Tube cap, glue heater
Tube base ring
Part 2
Maximum size
Part 3
Maximum size
Screen grid
Control grid
Screen grid
Figure A2FU251F type transmitting tube pin connection diagram
SJ20022—92
Appendix B
Visual inspection
(Supplement)
B1 The marking of the transmitting tube shall comply with the regulations, be clear and firm. B2 The welding seam of the transmitting tube shall be smooth and flat.
The anode radiator of the transmitting tube shall be evenly distributed and neatly arranged, and no obvious distortion and deformation shall be allowed. B3
The coating of the transmitting tube shall be bright, and no acid marks shall be allowed to remain. B5
The ceramic surface of the transmitting tube shall be clean.
Appendix C
Current distribution test method
(Supplement)
C1 Definition
C1.1 Current distribution
Electronic tube current distribution refers to the current flowing through each anode loop when the anode current reaches the specified value under the specified working conditions.
C1.2 Pulse emission current drop
Electronic tube pulse emission current drop refers to the drop value of the pulse trailing edge of the cathode pulse emission current to the top of the leading edge under the specified working conditions.
C2 Test principle diagram
Drum test tube
In the figure: P, P: a pulse voltmeter or oscilloscope 1R
ZWD a DC regulated power supply, the voltage should be kept stable within the pulse duration; S a single-pole four-position switch;
P a pulse signal generator;
R,~R, non-inductive resistor.
Additional Notes:
0.200..050
SJ20022-92
Appendix D
Constant Current Characteristic Curve
(Reference)
Anode Voltage (V)
Anode Current (A)
Curtain Grid Current (A)
Controlled Anode Current (A)
FU251F Transmitter Constant Current Characteristic Curve
This standard is proposed by the Science and Technology Quality Bureau of China Electronics Industry Corporation. This standard is under the jurisdiction of China Electronics Technology Standardization Institute. 0
(U350V)
This standard is drafted by China Electronics Technology Standardization Institute and Yichang Electronic Tube Factory. The main drafters of this standard are Tong Jinlin, Zhang Zhongquan, Hu Shanqiong and Sun Lixin. Project code: B91034.
The voltage of the transmitting tube should be connected in the following order and disconnected in the reverse order. Hot wire voltage
Control grid bias
—Anode voltage
Screen grid voltage
Pulse voltage
SJ20022-92
SJ20022-92
Appendix A
FU251F transmitting tube appearance and pin connection diagram (supplement)
Quality consistency inspection
Minimum size
Quality consistency inspection
Minimum size
FU251F transmitting tube appearance
* 4, 6, 8
Tube cap, glue heater
Tube base ring
Part 2
Maximum size
Part 3
Maximum size
Screen grid
Control grid
Screen grid
Figure A2FU251F type transmitting tube pin connection diagram
SJ20022—92
Appendix B
Visual inspection
(Supplement)
B1 The marking of the transmitting tube shall comply with the regulations, be clear and firm. B2 The welding seam of the transmitting tube shall be smooth and flat.
The anode radiator of the transmitting tube shall be evenly distributed and neatly arranged, and no obvious distortion and deformation shall be allowed. B3
The coating of the transmitting tube shall be bright, and no acid marks shall be allowed to remain. B5
The ceramic surface of the transmitting tube shall be clean.
Appendix C
Current distribution test method
(Supplement)
C1 Definition
C1.1 Current distribution
Electronic tube current distribution refers to the current flowing through each anode loop when the anode current reaches the specified value under the specified working conditions.
C1.2 Pulse emission current drop
Electronic tube pulse emission current drop refers to the drop value of the pulse trailing edge of the cathode pulse emission current to the top of the leading edge under the specified working conditions.
C2 Test principle diagram
Drum test tube
In the figure: P, P: a pulse voltmeter or oscilloscope 1R
ZWD a DC regulated power supply, the voltage should be kept stable within the pulse duration; S a single-pole four-position switch;
P a pulse signal generator;
R,~R, non-inductive resistor.
Additional Notes:
0.200..050
SJ20022-92
Appendix D
Constant Current Characteristic Curve
(Reference)
Anode Voltage (V)
Anode Current (A)
Curtain Grid Current (A)
Controlled Anode Current (A)
FU251F Transmitter Constant Current Characteristic Curve
This standard is proposed by the Science and Technology Quality Bureau of China Electronics Industry Corporation. This standard is under the jurisdiction of China Electronics Technology Standardization Institute. 0
(U350V)
This standard is drafted by China Electronics Technology Standardization Institute and Yichang Electronic Tube Factory. The main drafters of this standard are Tong Jinlin, Zhang Zhongquan, Hu Shanqiong and Sun Lixin. Project code: B91034.
The voltage of the transmitting tube should be connected in the following order and disconnected in the reverse order. Hot wire voltage
Control grid bias
—Anode voltage
Screen grid voltage
Pulse voltage
SJ20022-92
SJ20022-92
Appendix A
FU251F transmitting tube appearance and pin connection diagram (supplement)
Quality consistency inspection
Minimum size
Quality consistency inspection
Minimum size
FU251F transmitting tube appearance
* 4, 6, 8
Tube cap, glue heater
Tube base ring
Part 2
Maximum size
Part 3
Maximum size
Screen grid
Control grid
Screen grid
Figure A2FU251F type transmitting tube pin connection diagram
SJ20022—92
Appendix B
Visual inspection
(Supplement)
B1 The marking of the transmitting tube shall comply with the regulations, be clear and firm. B2 The welding seam of the transmitting tube shall be smooth and flat.
The anode radiator of the transmitting tube shall be evenly distributed and neatly arranged, and no obvious distortion and deformation shall be allowed. B3
The coating of the transmitting tube shall be bright, and no acid marks shall be allowed to remain. B5
The ceramic surface of the transmitting tube shall be clean.
Appendix C
Current distribution test method
(Supplement)
C1 Definition
C1.1 Current distribution
Electronic tube current distribution refers to the current flowing through each anode loop when the anode current reaches the specified value under the specified working conditions.
C1.2 Pulse emission current drop
Electronic tube pulse emission current drop refers to the drop value of the pulse trailing edge of the cathode pulse emission current to the top of the leading edge under the specified working conditions.
C2 Test principle diagram
Drum test tube
In the figure: P, P: a pulse voltmeter or oscilloscope 1R
ZWD a DC regulated power supply, the voltage should be kept stable within the pulse duration; S a single-pole four-position switch;
P a pulse signal generator;
R,~R, non-inductive resistor.
Additional Notes:
0.200..050
SJ20022-92
Appendix D
Constant Current Characteristic Curve
(Reference)
Anode Voltage (V)
Anode Current (A)
Curtain Grid Current (A)
Controlled Anode Current (A)
FU251F Transmitter Constant Current Characteristic Curve
This standard is proposed by the Science and Technology Quality Bureau of China Electronics Industry Corporation. This standard is under the jurisdiction of China Electronics Technology Standardization Institute. 0
(U350V)
This standard is drafted by China Electronics Technology Standardization Institute and Yichang Electronic Tube Factory. The main drafters of this standard are Tong Jinlin, Zhang Zhongquan, Hu Shanqiong and Sun Lixin. Project code: B91034.
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