CB Linear Amplifier | Electronic Project Circuits

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12 Watt CB linear amplifier

The amplifier has a wide bandwidth, from 1.8 MHz through to over 30 MHz. The drive level required is only about 2 – 5 mW under 14 MHz, rising to 10 mW at 30 MHz. You can therefore make a good QRP CW rig with nothing more than this PA and a simple crystal oscillator. I can achieve 12 watts out of mine using a 10-turn loop around my Grid Dip Oscillator! I can get over 15 watts from my Marconi signal generator, but above about 12 watts it is being over-driven an may not be very nice to look at on the spectrum analyser. The bias generator transistor, TR4, is marked TIP31 in the circuit diagram, but here you can use just about anything that will fit. You could even use another 2SC2078, if you had money to burn, but more practical components would be TIP41, TIP3055, MJE3055.

Read Source: http://w1.859.telia.com/~u85920178/tx/15w-pa.htm

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Categories: Power Amplifier, RF-Radio Frequency Tags: 27MHz RF Amp, CB linear amplifier

Antenna tunning circuit for 27MHz CB band

The antenna tunning circuit can accommodate 1/2 wave length antennas or higher, for input resistances of 50 Ohms which make it suitable for CB (Citizen Band) transceivers. C1 is for fine tunning and C2 is just for tunning. Turning C3 with the help of C2 you can set the SWR to 1:1. The Coil L is made of 11 turns of insulated copper wire with diameter of 1mm.