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Home Projects RF circuits CB receiver

 

 

CB receiver

source: Kyriakos Kontakos

 

TECHNICAL CHARACTERISTICS:

Tendency of catering: + 12V DC

Frequency of reception at AM: ~27MHz

 

 

 

Materially:

The resistances are 1/4W.

R1, R3, R5

100W

R2

56KW

R4

39KW

R6

560W

R7, R11

6,8KW

R8

220W

R9

2,2KW

R10

5,6KW

R12

10KW logarithmic pontesiometer

R13

1KW

R14

10W

C1

150pF ceramic

C2

39pF ceramic

C3, C5

12pF ceramic

C4

56pF ceramic

C6, C7, C8, C9, C10, C11, C16, C21

47nF ceramic

C12, C19

47mF/16V electrolytic

C13, C14

10nF ceramic

C15

100nF polyester

C17

10mF/16V electrolytic

C18

2,2mF/16V electrolytic

C20

470mF/16V electrolytic

D1

AA119, AA117 (germanium diode)

Q1, Q2

BF241 (amplifiers of intermediary frequency)

U1

SO42P (mixed and local oscillator)

U2

LM386 (amplifier A.F.)

Y1, Y2

Crystals hails. (You can you put the so much, those who also channels that you want you touch). See here.

MF1

Medium frequency 455KHz, core yellow. *

MF2

Medium frequency 455KHz, core white. *

MF3

Medium frequency 455KHz, core black. *

L1, L2

Wires of coper (smaltwme'na) with diameter 0,4mm wrapped in plastic support of diameter 6-7mm of perjstrofjkoy' core. For the L1 you wrap 13 coils. For the L2 you wrap 4 coils.

LS1

Loudspeaker 8W/1W.

ANT1

Aerial for CB (For the trials is enough a piece wire of few metres).

S1

Switch of choice of channel. It has so much places, those who also the channels that you want to touch.

* Intermediary frequencies mf1-3 you can him find in a old radio AM.

 

Regulations:

For the regulation needs a transmitter or generator in mpa'nta the CB, that is to say in the region 27MHz. If you have a certain friend with CB, you convince you to help.

    1. Connect a piece of cable around in the one metre in the place of aerial.

    2. Be supplied the receptor with + 12V and turn in half the potentiometer of regulation of sound (R12).

    3. Turn on the generator or the transmitter CB and you emit in distance of 10 metres roughly from the receptor, in the channel that receives the receptor..

    4. From the loudspeaker it will be supposed it begins to be heard what you emit and if it does not have big force, you turn the core of inductor L1/L2 until you have a increase of intensity. After this you can continue with the various medium frequencies beginning from black (MF3) until you have the biggest intensity. If it is heard mjkrofwnjsmo's, you lower little the intensity of loudspeaker or you remove the transmitter from the receptor.

Modification:

If you cannot find krysta'lloys you can make the modification that shows the form. That is to say, instead of crystal you in joint action put respectively coordinated circuits with LC each one in different channel.

L

Same with the L1.

C

4 - 40pF trimmer

Notes:

The receptor this can combine itself with the transmitter CB in order to you manufacture a complete station CB.

 

 

 
 

 
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