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Page: 6 Of 57
Model No: 3420
Drawing No:
Customer :
Model No:
H 520 PLUS
Rev. Date:
Modulation signal is fed to audio amplifier IC KIA324 and goes to TX voltage regulate circuit Q509, Q502, Q501 to
make nominal signal level to achieve wanted modulation. To control incoming audio signal, R272 and
corresponding ALC circuit limits the modulation shall not /-60% adjust RV702 +/-60% modulation under
1.0 KHz AF 60% mod plus 20 dB of audio signal.
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 Q102,Q103 mixes the incoming RF signal to generate first
IF signal. Mixed signals were filtered with the CF101 (10.695 MHz) crystal filter and other tuning circuits. Output
signal of mixer is filtered with CF102 (455 KHz ceramic filter). The 455 KHz signal from the 2
nd
IF filter was
amplified and limits internally. After amplification the signals fed the quadrature detector loop T104. Then we can
see the recovered audio signals on Pin 12 for FM and Pin 13 for AM of IC1.