UKW Sender mit 2N3553
By Rae XL Tkacik
This is the schematic for an FM transmitter with 3 to 3.5 W output
power that can be used between 90 and 110 MHz. Although the stability isn't
so bad, a PLL can be used on this circuit.
This is a circuit that I've build a few years ago for a friend, who used it
in combination with the BLY88 amplifier to obtain 20 W output power. From
the notes that I made at the original schematic, it worked fine with a SWR
of 1 : 1.05 (quite normal at my place with my antenna).
Schematic
|
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 |
|
Notes:
1. Email Rae XL
Tkacik with questions, comments, etc.
2. The circuit has been tested on a normal RF-testing breadboard (with one
side copper). Make some connections between the two sides. Build the
transmitter in a RF-proof casing, use good connectors and cable, make a
shielding between the different stages, and be aware of all the other RF
rules of building.
3. Q1 and Q5 should be cooled with a heat sink. The case-pin of Q4 should be
grounded.
4. C24 is for the frequency adjustment. The other trimmers must be adjusted
to maximum output power with minimum SWR and input current.
.
