3 WATT FM TRANSMITTER

3 Watt FM Transmitter

This is the schematic for a FM transmitter with 3 to 3.5 W yield control that can be utilized somewhere around 90 and 110 MHz. In spite of the fact that the steadiness isn't so terrible, a PLL can be utilized on this circuit. 

This is a circuit that I've construct a couple of years prior for a companion, who utilized it as a part of mix with the BLY88 speaker to acquire 20 W yield power. From the notes that I made at the first schematic, it worked fine with a SWR of 1 : 1.05 (truly ordinary at my place with my radio wire).

Part	Total Qty.	Description	Substitutions
R1,R4,R14,R15	4	10K 1/4W Resistor
R2,R3	2	22K 1/4W Resistor
R5,R13	2	3.9K 1/4W Resistor
R6,R11	2	680 Ohm 1/4W Resistor
R7	1	150 Ohm 1/4W Resistor
R8,R12	2	100 Ohm 1/4W Resistor
R9	1	68 Ohm 1/4W Resistor
R10	1	6.8K 1/4W Resistor
C1	1	4.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,C11,C12	7	100nF Ceramic Disc Capacitor
C6,C9,C10	3	10nF Ceramic Disc Capacitor
C8,C14	2	60pF Trimmer Capacitor
C13	1	82pF Ceramic Disc Capacitor
C15	1	27pF Ceramic Disc Capacitor
C16	1	22pF Ceramic Disc Capacitor
C17	1	10uF 25V Electrolytic Capacitor
C18	1	33pF Ceramic Disc Capacitor
C19	1	18pF Ceramic Disc Capacitor
C20	1	12pF Ceramic Disc Capacitor
C21,C22,C23,C24	4	40pF Trimmer Capacitor
C25	1	5pF Ceramic Disc Capacitor
L1	1	5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L9	5	6-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L8	3	1.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L10	1	8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D1	1	BB405	BB102 or equal (most varicaps with C = 2-20 pF [approx.] will do)
Q1	1	2N3866
Q2,Q4	2	2N2219A
Q3	1	BF115
Q5	1	2N3553
U1	1	7810 Regulator
MIC	1	Electret Microphone
MISC	1	PC Board, Wire For Antenna, Heatsinks

NOTE :

The circuit has been tried on an ordinary RF-testing breadboard (with one side copper). Make a few associations between the two sides. Fabricate the transmitter in a RF-confirmation packaging, utilize great connectors and link, make a protecting between the diverse stages, and be mindful of the various RF tenets of building. 

Q1 and Q5 ought to be cooled with a warmth sink. The case-pin of Q4 ought to be grounded. 

C24 is for the recurrence modification. Alternate trimmers must be changed in accordance with greatest yield power with least SWR and information current. 

Nearby laws in a few states, territories or nations may disallow the operation of this transmitter. Check with the neighborhood powers.