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.

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www.senderbau.egyptportal.ch

 

 

 

 .......alles für den eigenen UKW Radiosender: