TK-2360
9
1. Overview
The TK-2360 is a VHF portable transceiver designed to
Operate in the frequency range of 136~174MHz. The unit
consists of a receiver, transmitter, phase-locked loop (PLL)
frequency synthesizer, base band parts, power supply and
control circuits.
2. Frequency Confi guration
The receiver utilizes double conversion. The first IF is
49.95MHz and the second IF is 450kHz. The fi rst Local os-
cillator is supplied from the PLL circuit.
The PLL circuit in the transmitter generates the neces-
sary frequencies.
CIRCUIT DESCRIPTION
3. Receiver System
The receiver system is shown in Figure 2.
Fig. 1 Frequency confi guration
Fig. 2 Receiver system
TX/RX: 136~174MHz
185.95~
223.95MHz
136~174MHz
1st MIX
MCF
SP
MIC
CF
450kHz
ANT
ANT
SW
RF
AMP
IF
SYSTEM
X3
multiply
PLL
VCO
49.95MHz
50.4MHz
TX
AMP
RF
AMP
AF
AMP
MIC
AMP
Audio
processor
TCXO
16.8MHz
SP
ANT
IC401
IF,MIX,DET
Q406
1st MIX
CF401
CF402
ANT
SW
Q403
X3 multiply
2nd Local
X1
TCXO
16.8MHz
Audio
processor
IC812
TUNE
BPF
Q407
RF AMP
XF401
MCF
Q405
IF AMP
IC815
AF PA
TUNE
1st Local
BPF
3-1. Front End (RF Amplifi er) Circuit
The signal coming from the antenna passes through the
transmit/receive switching diode circuit (D201, D202, D203
and D204) and a BPF (L418 and L419), and is then amplifi ed
by the RF amplifi er (Q407).
The resulting signal passes through a BPF (L414 and
L416) and goes to the mixer. These BPFs are adjusted by
variable capacitors (D404, D405, D407 and D408). The input
voltage to the variable capacitor is a regulated voltage out-
put from the DC amplifi er (IC811).
3-2. First Mixer
The signal from the front end is mixed with the fi rst local
oscillator signal generated in the PLL circuit by Q406 to pro-
duce a fi rst IF frequency of 49.95 MHz.
The resulting signal passes through the XF401 MCF to
cut the adjacent spurious and provide the optimum charac-
teristics, such as adjacent frequency selectivity.