Model No: M150 Plus
Customer: INTEK Rev No: A
6
E. Receiver
CB receiver is dual conversion supper-heterodyne type with the first IF 10.695 MHz and second IF 455 KHz.
Receiver is separated two blocks, 1
st
IF section and 2
nd
IF section. The PLL synthesizer supplies first local
frequency 16.270 ~ 16.710 MHz.(for EU) and 16.90625 MHz ~ 17.29625 MHz (for UK) With the provided first
local frequencies to Q2,Q3 mixes the incoming RF signal to generate first IF signal. Mixed signals were filtered
with the XF1 (10.695 MHz) crystal filter and other tuning circuits. Output signal of mixer is filtered with CF1(455
KHz ceramic filter). The 455 KHz signal from the 2
nd
IF filter was amplified and limits internaly. After amplification
the signals fed the quadrature detector loop L20. Then we can see the recovered audio signals on Pin 9 for FM
of IC7. With the amplitude of recovered signals, Q10 serves as an audio amplifier. For AM signal Will be pass
filter CF1 and induced to Q6, Q7 respective and detected to voice signal by D5.
TROUBLESHOOTING HINTS
Symptom
Probable Cause
Remedy
Unit does not
work at all
•
Defective power switch VR1. • Blown fuse. •
Broken DC power cord. • Defective IC5.
•
Replace • Replace •
Replace • Replace
No output from
speaker at all
• Defective external speaker jack. •
Poor connection
on microphone connector • Defective push
switch on microphone. • Defective internal
speaker. • Defective VR1, IC8 other
components.
•
Repair or replace •
Repair or replace •
Repair or replace •
Replace • Replace the
defective components.
No noise on
speaker
•
Measure all the voltage of IC7 with voltage
chart • Defective squelch circuit components
(RV5,RV7,VR2 IC7)
•
Replace • Replace
Squelch does not
work
•
Defective VR2, RV5,RV7, IC3-D.
•
Replace the defective
components. • Re-adjust
