This standard specifies the test method for the output power of transmitting tubes for television. This standard applies to transmitting tubes for television transmitters. GB/T 3789.25-1991 Test method for electrical properties of transmitting tubes Test method for image output power GB/T3789.25-1991 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for electrical properties of transmitting tubes
Test methods for image output power
Measurements of the electrical properties of transmitting tubesMethods of measuring the vision output powerSubject and scope of application
This standard specifies the test methods for the output power of transmitting tubes for television. This standard applies to transmitting tubes for television transmitters. 2 Referenced standards
GB/T 3789. 12
General principles for test methods for electrical properties of transmitting tubes
GB6277 Measurement methods for television transmitters
3 Terms
Image output powerGB/T 3789. 25—91
Image output power refers to the power of one RF cycle during the synchronization level period when the transmitting tube is under the specified operating conditions and the load is optimally matched, that is, the image output power, which is called the synchronization peak power in this document. In actual measurement: the exciter is modulated with the full black signal in the full television signal. Then stimulate the tube under test. Measure the average output power of the transmitting tube, and then convert it to the synchronous top power according to formula (1). Pe
Ps= 12S + A(1-5)
: In the formula, 1 in the 13S term refers to the synchronous term amplitude as the reference, and 1 in the (1-8) term refers to one cycle as the reference. In the formula, Ps: - synchronous top power, W;
Pe—the average power output of the transmitting tube when modulated with full black level, W, - black level envelope level,
S—the percentage of the step level period relative to one line period (see Figure 1). ()
If the black level package level is 75%, that is, A=0.75; the sync pulse width is 4.7μs. The line period is 64us, that is, 8==0.073, then: P, - 1. 68P#
Approved by the State Administration of Technical Supervision on 1991-08-15-(2
Implemented on 1992-04-01
Test method
GB/T 3789.25—91
Figure 1 Waveform when measuring image output power
There are many methods for power measurement, such as base heat method, comparison method, variable resistance method, current resistance method, voltage resistance method, direct reading method, directional coupler method, etc. This standard recommends the following three measurement methods. 4.1 Calorimetry
The calorimetric method refers to a method of obtaining the load absorption power by measuring the coolant dissipation power when the heat dissipation element (such as a resistor) used as a load uses flowing water or other liquid as a coolant (or the flowing liquid itself is used as a heat dissipation element). The power consumed by the heat dissipation element can be calculated using the temperature rise, flow rate and performance parameters of the coolant according to the following formula (9): P:wwW.bzxz.Net
Where: P-
Dissipated power, W
Density, kg/L (the density of water is 1kg/L); -Specific heat capacity, J/(kg·℃) [The specific heat capacity of water is 4187J/
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