Kenwood TK-5810 Service Manual page 25

3-3. 1st IF
The 1st IF signal passes through the MCF (Monolithic
Crystal Filter) to remove unwanted signal.
The MCF has two paths (Wide band: XF201, Narrow
band: XF200), and these are controlled with the IF filter
switch (D208, D209, D210, D211, D212, D213, D214 and
D215).
The signal passes through the MCF (XF201) when the
Wide band (D209, D211, D213 and D215 are ON) is se-
lected. The signal passes through the MCF (XF200) when
the Narrow band (D208, D210, D212 and D214 are ON) is
selected.
Tripler
Q207
2nd Local
50.40MHz
IC209
Q205
FM IC
2nd IF
450kHz
3-5. 2nd IF
The 2nd IF signal passes through the ceramic fi lter to re-
move unwanted signal.
The ceramic fi lter has two paths (Wide band: CF201 and
CF202, Narrow/P25 band: CF200 and CF204), and these
are controlled with the multiplexers (IC201, IC202, IC203,
IC205, IC206 and IC207).
The control line is W/N1, W/N2 and VN.
IC205
W/N2
SW
IC206
SW
FM/P25
CIRCUIT DESCRIPTION
X200
VCXO
16.8MHz
WIDE
XF201
D214 NARROW
D215 XF200
SW
Fig. 3 1st IF and 2nd local
WIDE
CF201
NARROW/P25
IC201
CF200
W/N2
SW
IC202
SW
DET
L234
DET
DET
COIL
Fig. 4 2nd IF
TK-5810
The 1st IF signal passing through these MCFs is ampli-
fied by the IF amplifier (Q205) and goes into the FM IC
(IC209).
3-4. 2nd Local
The 1st IF signal (49.95MHz) amplifi ed by the IF ampli-
fi er (Q205) and the 2nd local signal (50.4MHz) generated by
tripling the reference oscillator frequency (16.8MHz) of the
VCXO (X200) by Q207, are mixed in the FM IC (IC209) to
produce a 2nd IF signal (450kHz) (Upper heterodyne).
D212 D210
Q204
D213 D211
SW SW
The signal passes through the ceramic fi lters (CF201 and
CF202) when the Wide band (W/N1: high level, W/N2: high
level, VN: high level) is selected. The signal passes through
the ceramic filters (CF200 and CF204) when the Narrow/
P25 band (W/N1: low level, W/N2: low level, VN: high level)
is selected.
After that, the signal is fed into ASIC (IC708) through ce-
ramic fi lter (CF100), and then, the signal is demodulated in
ASIC and the AF signal is dealing with DSP (IC701).
WIDE
CF202
W/N1
NARROW
IC203
CF204
SW
IC209
FM IC
BG /5810H
( )
WIDE
XF201
NARROW D208
XF200 D209
1st IF
SW
49.95MHz
W/N1
IC207
SW
2nd IF
450kHz
1st IF
49.95MHz
2nd Local OSC
50.4MHz
BG
( )
25