Kenwood TS-60S Service Manual page 2

CIRCUIT DESCRIPTION
Frequency Configuration
T
The TS-60s uses double conversion in all transmis-
sion modes, double conversion in all reception modes
except FM, and triple conversion in F M reception
mode. (Fg. 1) Table
1
Display frequency in each mode
Display
f r e q ~
Transmit carrler frequency
...
MIX-2 73.04SMHz MIX-1 B M
0 MIC
AM DET
MIX-1 73.045MHz MIX-2
RX
OUTPUT
Fig.
1
Frequency configuration
1
The receiver frequency in SSB mode is given by the
following equation when the receiver tone produced
by the input frequency ( f l ~ ) from the antenna is zero
beat (when an SSB signal with a carrier point of IN is
zeroed in):
IN
=
ILOI
-
f ~ o z
-
CAR
Since all these frequencies are generated by the
PLL circuit, as shown in Figure 2 (PLL frequency con-
figuration), the receiver frequency is determined only
by the reference frequency,
~ S T D ,
and the PLL divide
ratio. This means, the accuracy of the reference fre-
quency determines the accuracy of the operating fre-
quency of the transceiver.
The accuracy of the reference crystal oscillator used
in the TS-GOS is 10 ppm (-1 0 to +50°C). The accuracy
of the optional temperature-compensated crystal oscil-
lator (TCXO, SO-2) is 0.5 ppm (-1 0 to +50°C).
In SSB transmission mode or in other modes, the
frequency is determined by the reference frequency
(~STD)
and the PLL divide ratio. Table 1 lists the display
frequencies in the various modes.
The pitch of the incoming signal in CW mode can be
varied in 50-Hz steps in the range 400 to 1000Hz with-
out changing the center frequency of the IF filter (vari-
able CW pitch system).
FM transmission is carried out by applying the audio
signal from the microphone to the 62.35-MHzVCO and
modulating f ~ o z .
2
PLL Circuit Configuration
The TS-60s PLL circuit uses a reference frequency
of 20MHz. and covers 40 to 6OMHz (K), 50 to 54MHz
(E) in 5- to 200-Hz steps, depending on how fast the
encoder is turned. Figure 2 shows the frequency con-
figuration of the PLL circuit. Figure 3 is a PLL block dia-
gram.
1
1. Reference oscillator circuit
The reference frequency
( ~ S T D )
for frequency control
is generated by the 20-MHz crystal oscillator, X I and
Q12 (2SC2714(Y)). The reference frequencies for
other circuits are produced by dividing
~ S T D
by two and
by five by IC2 (pPD74HC390G).
~ S T D
is divided by two
to produce a 10-MHz PLL reference signal, which goes
to l C l l (CXD1225M) and lClOl (CXD1225M). It is in-
put to the CAR oscillator section t o produce a 10.695-
MHz signal. The 4-MHz signal produced by dividing
fSTD by five goes to IC4 (SN16913P).
The crystal oscillator circuit can be replaced by an
optional TCXO (SO-2). The TS-60s can be switched to
the TCXO by removing a shorting jumper ( W l N 2 ) .
1