Kenwood TR-7400A Service Manual page 39

0
L13
M
3.3 Adjustment of MIX Stage
3.4 Adjustment of Predrive
3.5 Adjustment of Tone Burst Time
PC Board
for Choke
(1) Connect the RF VTVM to TP3 of the TX unit and
key the transmitter. Adjust Lll,
and TC2 repeatedly for maximum indication.
(2) Set the frequency to 144.5 MHz and adjust VR6l on
the choke circuit board for maximum indication.
(3) Set the frequency to 146.5 MHz and adjust VR62 for
maximum indication.
(4) Set the frequency to 147.5 MHz and adjust VR63 for
maxlmum indication.
(1) Set the frequency to 146.0 MHz and connect the
power meter to the OUT terminal of the TX unit
(50 ohms).
(2) Adjust TC3 and TC4 of the TX unit for maximum
indication. The output level should then be 1.3 W
or more.
(1) Set the tone switch to BRU. Connecting an oscillo-
scope to TP2 of the TX unit in reception mode, plug
a tone burst oscillating element of 1,800 kHz into
the tone burst socket.
(2) Watching the waveform on the oscilloscope, make
surethatthe level is about.0.12 V with the AF VTVM.
(3) Watching the waveform, make sure that it diminishes
about 0.5 second after the transmitter is keyed.
If the delay is not as specified, adjust VR4 of the
TX unit.
VR5
TX UNIT
Fig. 16 Adjustment of PA Section, RF Meter and
Low Power
L12, L13, L14, TCl
Lower side
RX
UNIT