CB receiver

source: Kyriakos Kontakos

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.