Kenwood TS-2000 Service Manual page 20

TS-2000/X
Transmitter Final Amplifier
The final unit (X45-360 A/2) is composed of an HF and
VHF band final amplifier, an antenna turner matching circuit,
and a power supply circuit.
The LPF section and antenna tuner detection circuit are
located in the filter unit (X51-315).
The 1.8~144MHz band is amplified by the final unit, but it
operates in the broadband up to the drive amplifier. The
final unit amplifies signals using independent amplifiers in
the 8~50MHz and 144MHz bands. The amplifiers are
switched with a diode switch (D1).
Q1 : First stage amplifier
This amplifier uses a FET. It has frequency characteris-
tics so that the gain increases in the 144MHz band.
Q2 : Pre-drive amplifier
This amplifier uses a bi-polar transistor. It has unique fre-
quency characteristics.
Q3 and 4 : Drive amplifier
This is a push-pull type amplifier. It amplifies a signal
with a broadband up to the 144MHz band, then the signal is
branched to the HF and 144MHz bands through a relay.
Q6 and 7 : HF final amplifier
This amplifier uses a bipolar transistor with push-pull. It
amplifies a signal up to the 54MHz band, using an output
transformer with a coaxial cable. It outputs the signal to the
LPF section through an effective and light matching circuit in
the 50MHz band.
20
CIRCUIT DESCRIPTION
X51-315
144ANT
Q101,102
TX
LPF DET
144MHz
K2
VSF VSR
LPF section
Q101 and 102: 144MHz final amplifier
A 144MHz band signal passes through the HPF and en-
ters the branch circuit with two amplifiers.
It functions as a parallel amplifier that branches the signal
with the same phase, amplifies it with the Q101 and 102
amplifiers and re-synthesizes it. As a result a 100W output
is produced.
Since the output matching section is an LPF type, it at-
tenuates harmonics as well. After the output has been syn-
thesized, it detects the power of the progressive wave and
reflected wave with a directional coupler according to the
strip line, and outputs it to the LPF section.
LPF section
In the 1.8~50MHz band, the signal passes through the
LPF as shown in Table 3.
It has an independent LPF circuit and an antenna
changeover circuit for the 144MHz band.
The signal output from the LPF passes through the de-
tection circuits, the transmission/reception changeover re-
lay (K1), the antenna tuner changeover relay (K3) and the
antenna changeover relay (K4) and is output to ANT1 or
ANT2.
Select signal
2M
4M
7M
14M
21M
28M
50M
K1
D1
Q3,4 Q2 Q1
HPF
Final (X45-360 A/2)
Q6,7
Fig. 15
Frequency
1.8~ 2.0
2.0~ 4.1
4.1~ 7.5
7.5~14.5
14.5~21.5
21.5~30.0
49.0~54.0
X57-605
HFTX
X57-606
14TX