This standard specifies the test method for cathode emission current of transmitting tubes. This standard is applicable to the test of cathode emission current of space charge controlled oscillation, modulation, adjustment and power amplifier tubes with anode dissipation power above 25W. GB/T 3789.3-1991 Test method for electrical performance of transmitting tubes Test method for cathode emission current GB/T3789.3-1991 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods of the electrical properties of transmitting tubes
Test methods of cathode emission current
Measuring methods of cathode emission current Subject content and scope of application
This standard specifies the test methods of cathode emission current of transmitting tubes. GB/T 3789. 391
Replaces GB3789.3-83
This standard is applicable to the test of cathode emission current of space charge controlled oscillation, control, regulation and power amplifier tubes with anode dissipation power of more than 25W.
2 Reference standardsbzxz.net
GB/T3789.1 Test methods of electrical properties of transmitting tubes
3 Terms
cathodeemission current Cathode emission current refers to the current formed by electrons emitted by the cathode and flowing through other electrodes with positive potential to the cathode under specified working conditions.
Power supply schematic
DC test circuit schematic
Pulse test circuit schematic
Figure 3 Grid pulse test circuit schematic
Approved by the State Administration of Technology Supervision on 1991-08-15 and implemented on 1992-04-01
Figures 2 and 3:
GB/T 3789- 391
Pulse signal generator. Its internal resistance should meet the following requirements: When the current of the tube under test changes from zero to the maximum value, the change in output voltage should not be greater than 5%;
Non-inductive resistor, its error should not be greater than 1%, and the resistance value should meet the following requirements: R0.01
In:
The voltage applied to the anode when testing the cathode emission current: The minimum cathode emission current value specified in the product standard. Ce
A capacitor. The capacity should meet the following requirements:
Where: Pi
Pulse drop coefficient;
Chp'Rioin
Minimum internal resistance of the electron tube when it is turned on:
Pulse width.
R.——Resistor. The resistance value should meet the following requirements:
Where: T——Pulse period:
Pr, P2——Pulse voltmeter (or oscilloscope). 5 Test equipment and test rules
Test equipment and test rules should meet the requirements of GB/T3789, 1, 6 Test method
6.1 Test method of Figure 1
6.1.1 Add filament voltage according to the specification, increase the power supply voltage to the specified value, and the reading of the ammeter at this time is the cathode emission current. The test time of this method should not exceed 3 s. 6.1.2 If only the minimum value of cathode emission current is to be determined, the test sequence is as follows: add filament voltage according to the specification, adjust the power supply voltage until the reading of the ammeter reaches the specified minimum value of cathode emission current, read the voltage value, which should comply with the detailed specification. The test time of this method should not exceed 5 .6.2 Test method of Figure 2
6.2.1 Add filament voltage according to the specification, adjust the pulse voltage to the specified value, and then read the cathode emission current value on Table P:. 6.2.2 If only the minimum value of cathode emission current is to be determined, the test sequence is as follows: add filament voltage according to the specification, adjust the pulse voltage so that the reading of Table P reaches the minimum value of cathode emission current, read the pulse voltage value on Table P:, which should comply with the detailed specification. 6.3 Test method of Figure 3
Add filament voltage and DC voltage of each pole according to the specification, so that the tube under test is in the cut-off state, and then add a positive pulse voltage to the first grid, so that the first grid voltage is equal to the specified value, then the tube under test is turned on, and the cathode emission current value is read on Table P:. 6.4 For oxide cathode electrodes used in continuous operation, the measurement pulse width used is 100us, and for directly heated tungsten cathodes it is 10us. The pulse repetition frequency is specified in the detailed specification. Additional Notes
GB/T3789.3
This standard was 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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