27MHz CB radio amplifier circuit

The V-MOS FET number VN66AF (as Figure 1)is produce of the Siliconix company, for outstanding features are as durable and high gain. Most application of this is a normal power amplifier circuit. It can be used as the RF amplifier circuit.

the V-MOSFET no-VN66AF

Figure 1 the V-MOSFET no-VN66AF

How CB radio amplifier circuit works
This circuit (as Figure 2) is the RF frequency amateur amplifiers, 10M wavelength (26-36 MHz), require input about 200 mw and the power output of about 2-3 watts. The filter circuit at output can eliminate the noise up to 55dB and it without adjusting to use normal transmitter. Adjust P1 to control drain current of FET. We need the quiescent current in between 200 mA to 300 mA

the circuit diagram of this project
Figure 2 the circuit diagram of this project

For operation is linear (AM and SSB) to set the drain current to 20 mA. If use FM or CW will must adjust P1 until no quiescent current.
The FET should screw the heat sink.
the PCB and components layout
Figure 3 the PCB and components layout.

The parts you will need.
¼ W 5% Resistors
P1__________100K (potentiometer)
C1, C2______0.001uF 50V (ceramic)
C3, C4______150p 50V (ceramic)
C5_________47pF 50V (ceramic)
C6_________10uF 35V (Tantalum Electrolyte Capacitor)
C7_________0.022uF 50V (ceramic)
T1_________VN66AF (V-MOS FET)

Winding Coil
L1_________12 turns, magnet wire size 0.6 mm.
L2, L4______5 turns, magnet wire size 1 mm.
L3_________8 turns, magnet wire size 1 mm.

How to winding coil
To wind the wire each turns in no space on coilform inside diameter of about 9 mm.

How to learn electronics with simple ways

Related Posts


I always try to make Electronics Learning Easy.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Close Menu