Yaesu FT-227RB Instruction Manual page 23

P.O
Meter
LIULIII- 1771—
Audio
Oscillator
FT— 227RB
Deviation
Meter Meter
0
CM Coupler
( Dummy Load )
ANT
n
Osci I lo •
scope
Figure 8
ALIGNMENT
SOME OF THE FOLLOWING ALIGNMENT PRO-
CEDURES REQUIRE SPECIAL TEST EQUIP-
MENT AND TECHNIQUES AND SHOULD ONLY
BE DONE BY AN EXPERT TECHNICIAN.
( 5 )
TRANSMITTER
(1) RF Power Amplifier
a) Set the channel to 147.0 MHz. Connect a
YP-150 50 ohm dummy load/watt meter
to the antenna connector. Connect a
VTVM between TP1 and ground (1 V DC
range).
b) Key the transmitter and peak
T201
for
maximum VTVM reading.
(2) PO Meter
Set VR203 to the point where the S meter shows 8
with full output.
(3) AFP (Automatic Final Protection)
a) Connect the YP-150 to the antenna con-
nector. Set VR 2 0 5 to the extreme CCW
position. Connect the VTVM to cathode
(+) of
D208
and ground (—) and adjust
VR204 for minimum VTVM reading.
b) Disconnect the dummy load from the
antenna jack: Set VR205 to the fully
clockwise position. Key the transmitter,
and slowly rotate VR205 in a CCW
direction until the PO meter reading
becomes 4.
(4) Deviation
a) Connect YP-150 to the antenna connector,
the output of an audio oscillator between
pin 6 (hot) and 5 (ground) of microphone
receptacle and a deviation meter as illus-
trated in Fig. 8. Set the audio output level
to 25 mV at 1 kHz.
b) Connect a frequency counter between TP3
of the PLL unit and ground.
c) Key the transmitter by grounding pin 4 of
microphone receptacle. Adjust
T401
for a
10.7 MHz counter reading.
d) Set the output level of the audio signal
generator to 25 mV at 1 kHz and adjust
VR202 for ± 5 kHz deviation.
e) Set the audio level to 2.5 mV. Adjust
VR201 for a deviation of ± 2.5 kHz.
Tone Burst
a) Connect a YP-150 dummy load to the
antenna connector and disconnect the
microphone to prevent accidental voice
modulation.
b) Temporarily connect pin 5 of
Q215
to
pin 14.
c) Connect a YC-500 frequency counter to
the emitter of
Q216 ,
and set TONE BURST
switch to the ON position.
d) Key the transmitter and adjust VR2o7 to
the desired burst frequency.
e) Connect VTVM to MIC IN terminal and
adjust VR 209 for 2.5 mV VTVM reading.
f) Remove the wire temporarily connected in
step (b). Key the transmitter and adjust
VR208 for desired burst duration.