GB/T 3789.1-1991 General principles for testing the electrical properties of transmitting tubes
Some standard content:
National Standard of the People's Republic of China
Test Method of Electrical Properties of Transmitting Tubes
Measurernents of the Electrical Properties of trangmittlng tubes General 1 Subject Content and Scope of Application
GB/T3789.1-91
Replaces G 3789. 1. 83
This standard specifies the static electrical parameters and dynamic electrical properties of transmitting tubes, the requirements for test equipment and the test rules during testing. This standard applies to the test of static electrical parameters and dynamic electrical properties of space charge controlled vibration, modulation, adjustment and power amplifier tubes with anode dissipation power of more than 25W and transmitting tubes for television transmitting equipment (hereinafter referred to as electron tubes). 2 Reference Standards
GB2421 General Regulations for Basic Environmental Testing of Electrical and Electronic Products GB6277 Measurement Methods for Television Transmitters
3 Test Equipment
3.1 In addition to complying with this standard, the equipment used to test electron tubes shall also comply with the regulations and standards of relevant electrical equipment and technical safety requirements.
3.2 Requirements for the traceability test equipment that are not specified in this standard but are necessary in certain test methods should be specified in the test method: standard push or detailed specifications of the electron tube. 3.3 If the accuracy of the test equipment is affected by the external electromagnetic field or the test equipment interferes with other equipment and instruments, the surrounding environment of the test equipment should be shielded, and a filter device should be added to the power supply input end. 3.4 Parasitic oscillations are not allowed in the test equipment and preheating equipment. For this purpose, components that suppress parasitic oscillations can be connected to the test equipment and preheating equipment, but the test accuracy and preheating conditions must not be affected. 3.5 The insulation resistance between the leads of the tube socket of the tested tube should be no less than 200M2. The insulation resistance between the electrode circuits of the tested tube that are not connected to each other should be no less than 500M9. bzxZ.net
The DC voltage value for testing the insulation resistance should be no less than 500V. In water cooling or evaporative cooling systems, the insulating conduit installed on the electrode should ensure that the water leakage current is not greater than 1% of the electrode current, and its maximum value shall not exceed 100mA. For electrodes with negative potential, its value shall not exceed 10mA. If the above requirements cannot be met, measures should be taken, but the test accuracy shall not be affected.
3.6 If the DC voltage value and polarity of each electrode of the electron tube are not specified in the test standard or detailed specification, they refer to the common point of the circuit.
3.6.1 When testing directly heated electron tubes, the common point of the circuit should be: 3.6.1.1 When the filament power supply is DC, the common point of the circuit should be the filament lead connected to the negative terminal of the filament power supply. The detailed specification of the electron tube should indicate which lead of the filament is connected to the negative terminal of the power supply. 3.6.1.2 When the filament power supply is AC, the common point of the circuit should be the center point of the secondary coil of the filament power supply transformer or the center point of the voltage divider connected in parallel to the filament power supply.
Approved by the State Administration of Technical Supervision on August 15, 1991, and implemented on April 1, 1992
GB/T 3789. 1 - 91
3.6.2 When testing a indirectly heated electron tube, the cathode lead-out terminal of the tube under test is the common point. If a white bias resistor is connected to the cathode circuit, the circuit common point should be the end of the resistor that is not connected to the cathode. 3.7 When the DC power supply is connected to a circuit with an AC component, it must have a very small internal resistance to the AC component or be bypassed by a capacitor. The capacitor must meet the following requirements: When the AC component flows through, the voltage drop on the capacitor shall not exceed 1 of the total AC component, and the effective value of the AC component shall not exceed 1% of the DC voltage value.
3.8 If a test instrument, protective device and other components are connected to the electrode circuit with a positive potential to the cathode, when the electrode current is the specified value, the DC voltage drop generated on it shall not exceed 0.5% of the specified voltage of the electrode. 3.9: The voltage drop from the voltmeter measuring the filament voltage to the electronic replacement filament lead-out terminal (electronic burning filament pin) shall not exceed 0.2% of the specified value of the filament voltage. If this is not achieved, the voltmeter shall be connected across the filament lead-out terminal of the electron tube. 3.10 The air flow and direction, cooling water flow, temperature and pressure, evaporative cooling system and super-cooling system requirements for forced cooling of electron tubes shall comply with the provisions of the detailed specifications. 3.10.1 When testing naturally cooled electron tubes, there should be no partitions or other components in the test equipment close to the electron tube being tested that can cause the electron tube to overheat. If the tube being tested is in a closed box, there must be ventilation holes. 3.10.2 The cooling system of the test equipment for forced air cooling of electron tubes must be equipped with instruments for measuring air pressure and flow. 3.10.3 The cooling system of the test equipment for forced water cooling of electron tubes must be equipped with instruments for measuring the temperature of the inlet and outlet water, as well as the water flow.
3.10.4 For the test equipment of evaporative cooling electron tubes, the evaporative water pump of its cooling system should be able to meet the heat dissipation of the maximum power dissipated by the anode. The cooling system must be equipped with a device to keep the air pressure and water level of the water tank constant, as well as an instrument to measure the water flow and temperature after condensation. 3.10.5 For the test equipment of super evaporative cooling electron tubes, its cooling system must be equipped with a device to measure the temperature, pressure and water flow of the inlet and outlet water.
3.71 The electrical schematic diagram of the test equipment must comply with the electrical schematic diagram listed in the test standard, and the following points should be noted: 3.11.1 When multiple tube types are tested on a certain tube type with the same equipment, the redundant circuits may not be used, but the test accuracy shall not be affected. 3.11.2 Under the condition of ensuring safety, the instrument for measuring the anode current or the second grid current can be connected between the negative terminal of the power supply and the common point of the circuit, or between the positive terminal of the power supply and the electrode lead. 3.11.3 Under the condition of not affecting the test accuracy, the supply of the signal source can be fed in series or in parallel with the DC power supply. 3.12 The electrical test instruments on the equipment shall meet the following accuracy levels: 3.12.1 The DC instrument for electron tube testing shall not be lower than Class 1.5, and the first grid DC instrument and the DC instrument with bidirectional scale shall not be lower than Class 1.
3.12.2 The AC instrument for electron tube testing shall not be lower than Class 2.5, and the accuracy of the filament voltmeter shall not be lower than Class 1.5. In the AC power supply circuit, when using components that are prone to distortion, the selection of the AC instrument used ensures that its test accuracy meets the above requirements, otherwise the waveform distortion coefficient of the AC power supply should be less than 1%. 3.12.3. The error of the pulse voltmeter used for electron tube testing shall not be greater than 5%. : 3.12.4 The DC or AC instrument on the preheating equipment shall not be lower than Class 2.5. 3.13 When calibrating the electrical test instrument installed on the test equipment, in principle, the instrument should not be removed from the working position of the equipment, and should be lowered at the operating temperature of the equipment.
3.14 The range of the electrical test instrument should be selected so that the reading of the measured value must be greater than 1/3 of the range. The instrument for measuring the filament voltage should make the reading of the measured value greater than 1/2 of the range.
3.15 In order to protect the instrument from sudden overload; various protection devices are allowed to be used on the equipment, but they must not affect the test accuracy. 3.16 The DC power supply used by the equipment, especially the grid power supply, should generally adopt a voltage stabilizing device. Other forms of DC power supply, such as batteries and dry cells, are also allowed.
The first grid power supply should be connected to a discharge resistor, and its discharge current should be greater than the positive grid current. When there is a negative grid current in the second grid, a discharge resistor should also be connected, and its discharge current should be greater than the negative grid current. GB/T 3789. 1—91
3.-17 The power supply ripple factor measured at the tube socket under test shall comply with the following provisions: 3.17.1 When the anode dissipation power is less than or equal to 1kW, the ripple factor of the anode and auxiliary grid power supply shall be less than 1%: when the anode dissipation power is greater than 1 kW, the ripple factor shall be less than 5%. 3.17.2 The ripple factor of the first grid negative voltage power supply shall be less than 0.5%. 3.17.3 The ripple factor of the power supply for testing the cathode emission current shall be less than 5%. 3.18 For the DC voltage power supply used to supply the anode and the grid circuit with a positive potential to the cathode, when the load changes from zero to the maximum value, the change in power supply voltage caused by the internal resistance of the power supply shall not exceed 10%. For the power supply used to supply the filament, when the load changes from zero to the maximum value, the change in power supply voltage caused by the internal resistance of the power supply shall not exceed 3. 19
20%.
3.20 The pulse width and repetition frequency of the pulse power supply voltage shall comply with the provisions of the detailed specifications. 3.21 Pulse voltage, current waveform and parameter requirements shall comply with the provisions of Figure 1 and Table 1. Ap
Figure 1 Pulse voltage and current waveform
In the figure, A is the pulse amplitude. The average value of the pulse top determined by the height of the midpoint of the XY smooth line (excluding the top) drawn at the top of the pulse,
Pulse width. The time interval between the instantaneous value of the current or voltage when the pulse amplitude is 50%: pulse leading edge. The time required for the current or voltage to rise from 10% to 90% of the pulse amplitude; Fi
Note: pe
Pulse trailing edge. The time required for the current or voltage to drop from 90% to 10% of the pulse amplitude; pulse top drop. The difference between the pulse angles of the XT smooth line (excluding the top) drawn through the top of the pulse and the two intersections of the pulse waveform:
Top. A short-term sudden change in the pulse amplitude, the value of which is not greater than 5% of the pulse amplitude. Pulse top drop coefficient. The ratio of the pulse top drop to the pulse amplitude. Table
Pulse width
Pulse leading edge
Pulse trailing edge
Pulse term drop
Heat 5%A
1~10 μs
>10 μs
≤10%Ar
GB/T 3789.1—91
3.22 When measuring the dynamic electrical performance indicators of television transmitting tubes, the power supply, test load, test equipment, connection between the measuring equipment and the transmitter, requirements for the transmitter, and test signals shall comply with the provisions of GB 6277. 4 Test rules
4. The test specifications for card electronic tubes and the specific test methods adopted shall be specified in the detailed specifications. ,4.2 When testing electronic tubes, the voltages of each electrode shall be connected in the following order: filament voltage, grid voltage with negative potential to the cathode, anode voltage, and voltages of the remaining electrodes. The disconnection of the electrode voltages shall be carried out in the opposite order of connection or disconnected at the same time. 4.3 For electron tubes with filament current greater than 20A, the instantaneous value of the filament current should not exceed 1.5 times the specified value during the process of adjusting the filament voltage.
4.4 When testing electron tubes with forced cooling, the cooling system should be connected before applying the voltage to each pole. When the test is completed, the voltage to each pole should be disconnected first. If there is no provision in the detailed specification, the cooling system can be disconnected at least 5 minutes later. 4.5 If there is no provision in the test standard or detailed specification, when testing a single tube of a Lisheng tube without a common electrode lead-out line, the anode and other grids of the other single tube should be connected to the cathode. When testing a single tube of a Lisheng tube with a common auxiliary grid, the anode of the other single tube should be applied with the working point voltage, and a sufficiently large negative voltage should be applied to the first pole to make the cathode current of the single tube equal to zero. 4.6 The test should be carried out under normal atmospheric conditions specified in GB2421. Additional remarks:
This standard is proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard was drafted by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry and Factory 779.
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