13
TK-6110
CIRCUIT DESCRIPTION
Fig. 1
Frequency configuration
Fig. 2
Receiver section
1. Overview
The KENWOOD model TK-6110 is a VHF/FM 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 re-
ceiver, a transmitter, a phase-locked loop (PLL) frequency
synthesizer, power supply circuits, a control unit.
2. Circuit Configuration by Frequency
The receiver is a double-conversion superheterodyne
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.
The transmit signal is modulated PLL2-VCO2 (129.005
MHz) from the microphone. The transmit signal 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
An incoming signal from the antenna is applied to a band-
pass filter (L202) after going through a low-pass filter and an
antenna switch (K1). The signal is then amplified by the RF
amplifier (Q201) and again filtered by another band-pass fil-
ter (L203, L206 and L207).
3-2. First Mixer
The signal from the band-pass filter is heterodyned with
the first local oscillator signal from the PLL frequency syn-
thesizer circuit at the first mixer (IC201) to become a
128.55MHz first intermediate frequency (IF) signal.
The first IF signal is fed through two monolithic crystal
filters (XF201) to further remove spurious signals.
3-3. IF Amplifier
The first IF signal is amplified by Q202 and Q205, and
then enters IC202 (FM processing IC). The signal is hetero-
d y n e d a g a i n w i t h a s e c o n d l o c a l o s c i l l a t o r s i g n a l
(129.005MHz) with in IC202 to become a 455kHz second IF
signal. The second IF signal is fed through a 455kHz ce-
ramic filter, CF201 and CF202 to further eliminate unwanted
signals before it is amplified and FM detected in IC202.
ANT
TX/RX
29.7~37.0MHz : K
35.0~50.0MHz : K2
29.7~
37.0MHz : K
35.0~
50.0MHz : K2
LPF
ANT
SW
PA
AMP
TX
AMP
1st MIX
TX MIX
MCF
128.55MHz
CF
455kHz
FM IF
SYSTEM
AF
AMP
SP
129.005
MHz
129.005
MHz
PLL2
VCO2
PLL1
VCO1
MIC
AMP
MIC
158.25~165.55MHz : K
163.55~178.55MHz : K2
158.705~166.005MHz : K
164.005~179.005MHz : K2
T/R
SW
BPF
Q201
RF AMP
BPF
BPF
LPF
IC201
1st MIX
D502
MCF
128.55MHz
Q205
IF AMP
Q202
IF AMP
IC202
FM IF SYSTEM
CF201,202
455kHz
129.005MHz
XF201
Item
Rating
Nominal center frequency
128.55MHz
Pass bandwidth
±
7.5kHz or more at 3dB
Attenuation bandwidth
±
35kHz or less at 40dB
Ripple
1.0dB or less
Insertion loss
5dB or less
Guaranteed attenuation
70dB or more at fo
±
910kHz
Terminating impedance
1000
Ω
Table 1
Crystal filter (L71-0560-05)
(TX-RX unit XF201)
