Lo2 (The Second Local Oscillator); Lo3 (The Third Local Oscillator); Reference Signal Generator, Lo1/ Lo2/ Lo3 - Kenwood TS-590S Service Manual

TS-590S
and then goes through BPF and is output as LO1. When
RX-2 path is selected or when transmitting, 36.5625MHz to
66.5475MHz is output, amplifi ed by the broad band ampli-
fi er (IC804), and then doubled in the multiplier (D652), goes
through BPF, and is output as 73.120MHz to 133.095MHz
LO1.

■ LO2 (the second local oscillator)

The reference oscillating circuit's output signal 15.6MHz
signal passes through a buffer (Q502) and is doubled in
a multiplier (Q503) to generate a 31.2MHz signal. The
31.2MHz signal is also used as the DDS (IC601)'s reference
Q808
IC803
DDS
Buffer
X502,Q501
15.6MHz
Option
SO-3
6
CIRCUIT DESCRIPTION
D659
LPF
D651
IC804
AMP
Q502 Q503 Q504,Q505 Q506
Buffer Doubler Doubler Buffer
Q601
IC601
DDS
Buffer
Fig. 2 Reference signal generator, LO1/ LO2/ LO3
frequency, and therefore its resistance is divided. Then, the
31.2MHz signal is doubled in multipliers (Q504, Q505) to
generate a 62.4MHz signal.
The 62.4MHz signal's high harmonic is cut in the BPF
and the signal is amplifi ed in the amplifi er (Q506) to gener-
ate LO2. If IFB is selected, the diode switch (D501) cuts the
LO2 output.

■ LO3 (the third local oscillator)

The LO3 used in the modulator and the detector is gen-
erated in the DDS (IC601). The DDS output signal passes
through the buffer (Q602) and LPF to generate LO3.
BPF
D680 D681
Q663
BPF
D653 D679
AMP
BPF
D657 D662
D655
HPF
D671
D669
D654
D652
L651
D670
Doubler
Q801 LPF
IC801
PLL
Buffer
Q804
LPF
Buffer
D501
Q602 LPF
Buffer
D667
LO1
LPF
LPF
D660
LPF
D663
LPF
D661
BPF
D668
BPF
Q806
VCO
FM MOD
LO2
LO3