4 Watt FM Transmitter

Copyright of this circuit belongs to smart kit electronics. In this page we will use this circuit to discuss for improvements and we will introduce some changes based on original schematic.

Parts List

R1 = 220K
R2 = 4,7K
R3 = R4 = 10K
R5 = 82 Ohm
R = 150Ohm 1/2W x2 *
VR1 = 22K trimmer

C1 = C2 = 4,7uF 25V electrolytic
C3 = C13 = 4,7nF ceramic
C4 = C14 = 1nF ceramic
C5 = C6 = 470pF ceramic
C7 = 11pF ceramic
C8 = 3-10pF trimmer
C9 = C12 = 7-35pF trimmer
C10 = C11 = 10-60pF trimmer
C15 = 4-20pF trimmer
C16 = 22nF ceramic *

L1 = 4 turns of silver coated wire at 5,5mm diameter
L2 = 6 turns of silver coated wire at 5,5mm diameter
L3 = 3 turns of silver coated wire at 5,5mm diameter
L4 = printed on PCB
L5 = 5 turns of silver coated wire at 7,5mm diameter

RFC1=RFC2=RFC3= VK200 RFC tsok

TR1 = TR2 = 2N2219 NPN
TR3 = 2N3553 NPN
TR4 = BC547/BC548 NPN
D1 = 1N4148 diode *
MIC = crystalic microphone

Note: Parts marked with * are used for the tune-up of the transmitter in case you have not a stationary wave bridge.