Yaesu FT-857 HF, Техническое дополнение

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14
Alignment
PLL Unlock
1. Connect the DC voltmeter to TP1029 on the MAIN
Unit (or pin 11 of
J2002
on the PLL Unit).
2. Disconnect the REF Unit from the MAIN Unit; con-
firm that the DC voltmeter shows less than 0.5 V and
that “
UNLOCK
” is displayed on the LCD.
3. Re-connect the REF Unit to the MAIN Unit, and con-
firm that the DC voltmeter shows at least 3.5 V and
that the LCD returns to its normal display.
Idling Current Adjustment
Before alignment, set the mode to CW and tune the trans-
ceiver to 1.800 MHz. Nothing should be connected to the
CW Key Jack, and switch off
S1001 on the MAIN Unit.
Pre-Driver Stage Idling Current
1. Connect the ammeter between
TP1019
(+) and
TP1020 (–) on the MAIN Unit.
2. Press the PTT, and adjust
VR1004
for an indication
of 35 mA (±2 mA) on the ammeter.
Driver Stage Idling Current
1. Connect the ammeter between
TP1017
(+) and
TP1018 (–) on the MAIN Unit.
2. Press the PTT and adjust
VR1003
for an indication of
30 mA (±2mA) on the ammeter.
Exciter Stage Idling Current
1. Disconnect the Jumper Plug from J1004 on the MAIN
Unit, then connect the ammeter to
J1004
(pin 1: –,
pin 1: +).
2. Turn both
VR1001
and
VR1002
fully counterclock-
wise.
3. Press the PTT and adjust
VR1002
for an indication of
100mA (±10 mA) on the ammeter.
4. Press the PTT and adjust
VR1001
for an indication of
200mA (±10 mA) on the ammeter.
5. Re-connect the Jumper Plug to
J1004
and switch on
S1001.
TX IF Adjustment
SSB/CW TX IF Adjustment
1. Tune the frequency to the 14 MHz band. Connect the
RF millivoltmeter to
TP1033
on the MAIN Unit.
2. Disconnect the Coaxial Cable from J1002 and termi-
nate
J1002
into a 50-Ohm dummy load.
3. Inject a 1 kHz tone at 1 mV level to
the
MIC
jack.
4. Key the transmitter, and adjust T1033
for maximum indication on the RF
millivoltmeter.
5. Disconnect the 50-Ohm dummy load
and re-connect the Coaxial Cable to J1002 .
GND
PTT
MIC MIC GND
MAIN Unit Alignment Points II
T1021
S1001 TP1017
TP1018
TP1019
TP1020
VR1003
VR1004
VR1002
VR1001
J1004
TP1033
T1033
J1002
T1014
TP1027
T1023
L1049
VR1005
T1013 T1012 T1011
J1003