Kenwood TS-900 Operating Manual page 37

5.13 RF SECTION (X44-1020-10) (See Figure 34)
The RF amplifier stage of the TS-900 is part of the RF
section. The RF section includes four coil-pack circuit
boards which are interconnected by an 18-prong connector.
The transmitter's second IF signal is mixed with the output
of the heterodyne oscillator to produce the final frequency.
This signal is amplified by V1 (6GK6) to drive the two
6LQ6 final power tubes.
Received signals are amplified by transistor Q3, and
heterodyned by transistor Q2 to the receiver's first IF
signal.
The input and output of the RF section are coupled to the
MIX board through a tuner which uses a voltage variable
capacitor.
HET OSC (Heterodyne Oscillator) Board
(X50-1040-10) (See Figure 35)
This circuit employs a crystal and an FET (Q1) to generate
a stable oscillator output. This output is fed through a
buffer amplifier (Q2 and Q3) to the heterodyne mixer.
MIX COIL BOARD (X44-1030-10) (See Figure 36)
This board holds the tuning coils for heterodyning in
transmit and receive.
ANT COIL BOARD (X44-1040-10) (See Figure 37)
This board holds the front-end coils of the receiver section.
DRIVE COIL BOARD (X44-1050-10) (See Figure
38)
This board holds the transmitting coils. The board serves as
a load for the 6GK6 driver and as a driver for the two 6LO6
final tubes. There is no WWV coil for the transmitter
section.
32
Qi——
TP1——_
Q2.——
TC
HET OSC
Unit
T3
TI
S2-1
TCs, X9 (29. 5MHz)
TCs, X8(29.0MHz)
TC7, X7 (28. 5MHz)
TC6, X6 (28. 0MHz)
TCs, X5 (21MHz)
TC4, X4 (14MHz)
TC3, X3 ( 7 MHz)
TC2, X2 (3.5MHz)
TC1, X1 (WWV)
Q3
FIGURE 35. HET OSC