12
TK-190
ANT
TX/RX
29.7~37.0MHz : K
35.0~50.0MHz : K2
ANT
SW
PA
AMP
MIC
AMP
TX
AMP
AF
AMP
ANT
SW
1st MIX
158.25~165.55MHz : K
163.55~178.55MHz : K2
MCF
128.55MHz
FM IF
SYSTEM
129.005MHz
SP
PLL1
VCO1
PLL2
VCO2
MIC
CF
455kHz
TX MIX
29.7~37.0MHz : K
35.0~50.0MHz : K2
129.005MHz
158.705 ~166.005MHz : K
164.005 ~179.005MHz : K2
Fig. 1
Frequency configuration
T/R
SW
BPF
Q200
RF AMP
BPF
BPF
LPF
1st MIX
D102
MCF
128.55MHz
Q302
IF AMP
IC300
FM IF SYSTEM
CF300
455kHz
129.005MHz
Fig. 2
Receiver section
Item
Rating
Nominal center frequency
128.55MHz
Pass band width
±
5~7kHz or more at 3dB
Attenuation band width
±
25kHz or less at 3dB
Ripple
1.0dB or less
Insertion loss
6dB or less
Guaranteed attenuation
80dB or more at fo
±
910kHz
40dB or more within fo
±
1MHz
Terminating impedance
600
Ω
Table 1
Crystal filter XF300 (L71-0559-05)
CIRCUIT DESCRIPTION
1. Overview
The KENWOOD model TK-190 is a VHF/FM hand-held
transceiver designed to operate in the frequency range of
29.7 to 37MHz(K),35.0 to 50.0MHz(K2), the unit consists of
a receiver, a transmitter, a phase-locked loop(PLL) fre-
quency synthesizer, power supply circuit, a control unit.
2. Circuit Configuration by Frequency
The receiver is a double-conversion super-heterodyne
with a first intermediate frequency (IF) of 128.55MHz and a
second IF of 455kHz. Incoming a signals from the antenna
are mixed with the local signal from the PLL1 to produce the
first IF of 128.55MHz.
This is then mixed with the 129.005MHz seconds local
oscillator output to produce the 455kHz second IF. This is
detected to give the demodulated signal.
T h e t r a n s m i t s i g n a l i s m o d u l a t e d P L L 2 -
VCO2(129.005MHz) from the microphone. The transmit sig-
nal frequency is down-conversion with PLL2 and PLL1. It is
then amplified and sent to the antenna.
3. Receiver System
3-1. Front-end RF amplifier
The signal are then passed through an antenna matching
coil, where the high-frequency components are amplified by
a MES FET(Q200). The signals are then fed into band-pass
filter that uses varactor diode tuning to reject unwanted sig-
nal components, and is fed to the 1st mixer.
3-2. First mixer
The 1st mixer uses the GaAs IC (IC200). The 1st mixer
mixes the signal with the 1st local oscillator frequency from
the VCO1, and converts to the 1st IF (128.55MHz).
The signal then passes through monolithic crystal filter
(XF300) to remove unnecessary nearby frequency compo-
nents. The signal from the MCF is used as the 1st IF signal.
3-3. IF amplifier
The 1st IF signal is amplified (Q302) and fed into IC300 in
the FM IC. The IF signal is then mixed with the 2nd local
oscillator frequency of 129.005MHz to generate the 2nd IF
of 455kHz. The 455kHz signal is then passed through a ce-
ramic filter (CF300) and fed back into IC300 for additional
amplification.
