Kenwood TS-2000, Service Manual

Page: 13 / 171

13
TS-2000/X
■
Speaker output changeover
When external speakers 1 and 2 and headphones are
connected, you can change over the sub/main band outputs.
The headphone connection is preferred over the all the
speaker output and you can select from three patterns for
headphone left-right changeover.
Connection Conditions (
●
: connected) Output condition by connection of left table
Headphone SP1 SP2 Headphone Built-in speaker SP1 SP2
●
X X
→
Pattern 0~2 Stop X X
● ●
X
→
Pattern 0~2 Stop Stop X
● ● ●
→
Pattern 0~2 Stop Stop Stop
●
X
●
→
Pattern 0~2 Stop X Stop
X
● ●
→
X Stop Pattern 0~2 (Left) Pattern 0~2 (Right)
X X
●
→
X Pattern 0~2 (Left) X Pattern 0~2 (Right)
X
●
X
→
X Stop Main-sub full mix X
X X X
→
X Main-sub full mix X X
Left-right output patterns
In case of headphones In case of SP1 & SP2
Selected Pattern Left side Right side SP1 or Built-in SP2
Pattern 0 Main-sub full mox Main-sub full mix Main-sub full mix Main-sub full mix
Pattern 1 Main : Full sound Main : 1/4 sound main : Full sound Main : 1/4 sound
Sub : 1/4 sound Sub : Full sound Sub : 1/4 sound Sub : Full sound
Pattern 2 Main Sub main Sub
This is a reverse function and left-right changeover is possible.
When SP1 only has been connected, the built-in speaker
will change over to SP1.
When SP1 and SP2 are connected, you can select the
SP1 and SP2 output method from three patterns, the same
as for the headphones.
Table 14
Main VHF/UHF Band Front-End and
Sub Receiver System
The VHF and UHF band receiver circuit is configured with
two systems, a main band (FM/ AM/ SSB/ CW/ FSK) and a
sub-band (FM/AM), each of which has a VHF and a UHF
band path.
In the main band, the first IF is 41.895MHz and the sec-
ond IF is 10.695MHz and the signal lower hetero to the sec-
ond IF is sent to the TX-RX1 unit (X57-605) and linked to the
second IF, which is shared by the other bands. The sub-
band is a double conversion where the first IF is 58.525MHz
and the second IF is 455kHz. It is configured so that de-
tected AF signals are sent to the control unit (X53-391).
■
VHF/ UHF band front end
The circuit operation of the sub-receiver unit differs de-
pending on whether it is for K destination or others. The
circuit operation for each of the destinations is described
below.
• K destination
The incoming signal from the VHF band antenna terminal
passes through the TX/RX changeover relay (K2) in the filter
unit (X51-315) and goes to the TX-RX2 unit (X57-606). Then,
it passes through the 12dB ATT circuit and is divided to the
136~155MHz path and the 118~136MHz, 155~174MHz
and 220~300MHz path by the L distribution circuit. The
136~155MHz signal passes through a 2-pole BPF (band-
pass filter) and enters the pre-amplifier (Q15). The ampli-
fied receive signal is again distributed to the paths for the
main and sub receiver units by the L distribution circuit.
The signal distributed to the main receiver unit passes
through the 2-pole variable tuning BPF, is amplified by the
second amplifier (Q24) and goes to the mixer (IC4) for the
main band common to the VHF and UHF bands through the
variable tuning BPF. The 2-pole x 2-stage BPF for the main
band VHF controls the tuning frequency by output from the
D/A of the TX-RX1 unit (X57-605).
CIRCUIT DESCRIPTION