5 - 2
• RX AF CIRCUITS
AF CIRCUITS
The demodulated AF signals from the IF IC (IC1) are
amplified and filtered by the HPF (IC16), and passed
through the AF line SW (IC14) and LPF (IC16). The filtered
AF signals are adjusted its level (=loudness) by the D/A
converter (IC18), and applied to the AF AMP (IC15) via the
AF line SW (IC14).
The amplified AF signals are applied to the AF power AMP
(IC8) and power-amplified to obtain AF output level.
The power-amplified AF signals are applied to the internal
speaker on the FRONT UNIT or output from the external
speaker jack on the rear panel.
SIGNALING (DECODING)
Demodulated signals from pin 9 of the IF IC (IC1) are
passed through the LPF to extract tone signals contained in
the demodulated signals.
2/5 tone signals are extracted by the LPF (IC16). CTCSS/
DTCS signals are extracted by the LPF (Q39).
These extracted tone signals are applied to the CPU (FRONT
UNIT: IC1) for decoding.
LPF
IC16
LPF
IC16
LPF
Q39
HPF
IC16
AF
AMP
IC15
AF
POWER
AMP
IC8
LA4425A
AF
MUTE
Q35,36,D29
Int. speaker
Ext. speaker jack
J4
ANALOG
SW
SDEC
To CPU (FRONT UNIT: IC1)
CDEC
IC14
CD4066
D/A
IC18
AK2330
(2/5 TONE signals)
(TCSS/DTCS signals)
FRONT UNIT
AF ON
DISC
From the IF IC
DISC
DISC
VRAF
TMONI
RXAF
