4
TK-3130/3131
Frequency Configuration
Fig. 1
Frequency configuration
ANT
SW
BPF
MIX, IF
DET
AF
AMP
TCXO
RF
AMP
RF
AMP
MIC
AMP
PLL VCO
1st MIX
CF
450kHz
38.85MHz
MCF
38.4MHz
SP
MIC
ANT
460~470MHz
460~470MHz
421.15~
431.15MHz
RF
AMP
Tripler
X3
12.8MHz
Reception method
Double super heterodyne
1st IF frequency
38.85MHz
2nd IF frequency
450kHz
Transmission method
VCO direct oscillation amplification
Modulation
Variable reactance phase modulation
Table 1
Basic configuration
Receiver System
■
Front End
The high-frequency signal from the antenna passes
through a low-pass filter and a high-frequency switch (D12,
L25 and D13) which switches between transmission and re-
ception, and goes to the BPF (L42) to remove unwanted sig-
nals. The resulting signal is amplified by high-frequency am-
plifier (Q18) and goes to the first mixer (Q19).
■
First Mixer
The signal that reaches Q19 is mixed with the first local
signal from the VCO to produce a first IF signal (38.85MHz).
(Receive frequency – First local frequency
= First IF frequency = 38.85MHz)
The first IF signal passes through MCF: XF1 (monolithic
crystal filter) to remove unwanted signals.
The first IF signal is amplified by IF amplifier (Q20) and
goes to IF IC (IC2).
CIRCUIT DESCRIPTION
Item
Rating
Nominal center frequency (fo)
38.85MHz
Pass bandwidth
±
5.0kHz or more at 3dB
Attenuation bandwidth
±
18.5kHz or less at 35dB
Ripple
1.0dB or less
Insertion loss
4.0dB or less
Guaranteed attenuation
70dB or more at fo–900kHz
Terminating impedance
610
Ω±
10% / 3.0pF
±
0.5pF
Table 2
MCF (L71-0586-05) : TX-RX unit (B/2) XF1
Item
Rating
Nominal center frequency (fo)
450kHz
6dB bandwidth
±
6.0kHz or more
50dB bandwidth
±
12.5kHz or less
Ripple (at 450kHz
±
4kHz)
2dB or less
Guaranteed attenuation
35dB or more
(at 450kHz
±
100kHz)
Insertion loss
6dB or less
I/O matching impedance
2.0k
Ω
Table 3 Ceramic filter (L72-0958-05) : TX-RX unit (B/2) CF1
Fig. 2
Receiver section configuration
Fig. 3
Receiver circuit
ANT
LPF
3T
3R
D12
L25
D13
L42
BPF
Q18
3R
IF IC
Q20
XF1
3R
1st IF : 38.85MHz
Q19
VCO
1st local
OSC
BPF
L42
RF AMP
Q18
1st MIXER
Q19
MCF
XF1
IF AMP
Q20
IF AMP, DET
IC2
AF AMP
IC208
SP
1st local OSC (PLL)
2nd local OSC
ANT
38.85MHz
465.0MHz
D12
D13
L25
LPF
ANT
SW
Содержание TK-3130 - ProTalk XLS UHF
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