C1942 15W transmitter power amplifying circuit, 15W RF Power Amplifier
Keywords: 15W RF power amplifying circuit, RF power amplifier
The power amplifier can extend the power of 1-2W, 88-108MHz frequency modulated transmitter so that the power of 10-15W is made of single tube amplification and multi-level low-pass filter, with high conversion efficiency and strong Wave
Inhibitory capabilities. The circuit is shown in the drawing, which uses high-power emission tubes C1972, which are as follows: 175MHz, 4A, 25W, power gain ≥ 8.5dB, according to the parameters shown in the figure, the circuit work center frequency is approximately 98MHz, input about 2W
When RF power, the rated output is up to 15W. In order to protect any of the 88 ~ 108MHz, the output reaches the rated value, and the partial element can be appropriately adjusted according to the center frequency of the predecessor. If necessary, reduce low-pass bass
The number of cases to increase the output power. The extended power signal is fed from the three-stage low pass filter to the high-level oligible wave ingredients.
Component Selection: Except for electrolytic capacitors, other high-frequency porcelain capacitors, C11, C12, C14 have high frequency characteristics, stable capacitors, combined inductors RFC1, RFC2 with finished inductor, must pay attention to
The current load carrying capacity of RFC2 should be used in a thicker inductor with a thick core. L1-L6 can be made of Ø0.8mm high-strength enamel coating, with a diameter of about 5mm, and the circle is indicated in "T" in units. Q1 with ordinary Q9 socket
Use with plug. Q2 uses a dedicated 50Ω RF output connector, and the remembering resistance is smaller, more beneficial to impedance matching. Power amplification pipe uses a relatively common emission dedicated tube C1972, of course, if your silver is particularly sufficient,
If you buy a high gain tube such as C2538, the power will be larger. When the circuit is debugging, it is important to pay attention to the circuit power, it must be connected to the fake load (I use 30 of 1W, 1500Ω high-precision metal film resistance, and there is enough heat sink, normal working normally
The source power is not less than 2.5A, and the antenna impedance is strict equal to 50Ω. It cannot be pulled with a short rod, otherwise the strong RF feedback current will cause the circuit to cause itself, most of the RF energy cannot be irradiated to the space and consume power.
In the tube, it is overheated damage; the special coaxial electricity display must be transmitted to the outdoor antenna via 50Ω emission. Whether the circuit can work properly is that the circuit's debugging, the whole process is very careful. Only when you debug
The excitation power, the power supply voltage drops by 9V, and the high-frequency voltage meter (cannot be used in ordinary meter), adjusting the high-frequency voltage value of the fake load, adjusting C12, C14, L3, L4, L5, L6, so that the voltage amplitude is 15- 20V
Around, adjust C11, L1 to maximize the voltage. Then gradually increase the voltage, each increases the primary voltage repeatedly to adjust the highest output voltage, pay attention to the voltage and radio frequency input excitation
The rate is synchronized to ensure accuracy of debugging results. When reaching the rated value, the power supply voltage is about 2A lower, and the 50Ω pure electric block load is ≥40V, and the radio frequency output power is 15W. With this RF power amplifier, 50Ω umbroof-shaped vertically vertical emission antenna (gain is about 2 dB), tested in a normal FM radio, and the emission distance coverage is not less than 15km.
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