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1.3W Power Amplifier

1.3W Power Amplifier

This is basically an RF amplifier. It will amplify the RF signal about 10 times 100mW in to 1.3W out.This amplifier is based on the transistor 2SC1970 and 2N4427
RF power The output power is about 1.3W and the input driving power is 30-50mW. You can use other transistor as 2SC1971 and get much more output power. 1.3W will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. Make sure it can take up to 5-10W, else it will be a hot resistor. You MUST use an antenna or 50 ohm dummy resistor while testing else you burn up the transistor. As you can see there are several variable capacitor and coils in this construction and it must be so.It is adviced to put all in middle range before you apply power. To tune this amplifier you can either use a wattmeter, SWR unit or you can do as the author did using a RF field meter.
Good grounding is very important in a RF system. He used bottom layer as Ground and he connected it with the top with wires to get a good grounding. Make sure you have some cooling at the transistor. In my case he had put the 2SC1970 close to the PCB to handle the heat. With good tuning the transistor shouldn’t become hot.

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