Yaesu FT-857 series, Technical Supplement

Page: 17 / 82

17
Alignment
Power Amplifier Adjustment
HF/50 MHz Idling Current Adjustment
1. Connect the 50-Ohm dummy load to the HF/50 MHz
antenna jack.
2. Tune the transceiver to any HF band, or to the 50 MHz
band.
3. Disconnect the wire jumper from
TP3025
and
TP3026 on the PA Unit, then connect the ammeter
between
TP3025
(+) and
TP3026
(–).
4. Turn VR3001 fully counterclockwise.
5. Press the PTT, and adjust
VR3001
for an indication
of 300 mA (±10 mA) on the ammeter.
6. Disconnect the ammeter, and re-connect
TP3025
and
TP3026 using the wire jumper.
V/UHF Idling Current Adjustment
1. Connect the 50-Ohm dummy load to the 144/430 MHz
antenna jack.
2. Tune the transceiver to the 430 MHz band.
3. Disconnect the wire jumper from
TP3025 and
TP3026
on the PA Unit, then connect the ammeter
between TP3025 (+) and TP3026 (–).
4. Turn
VR3002
fully counterclockwise.
5. Press the PTT, and adjust VR3002 for an indication
of 300 mA (±10 mA) on the ammeter.
6. Disconnect the ammeter, and re-connect TP3025 and
TP3026
using the wire jumper.
Directional Coupler Balance Adjustment
1. Connect the 50-Ohm dummy load to the HF/50 MHz
antenna jack.
2. Tune the transceiver to 28 MHz band in the CW mode,
and connect the DC voltmeter to
TP3003
on the PA
Unit.
3. Press the PTT, and adjust
TC3002
for minimum indi-
cation on the DC voltmeter.
4. Connect the 50-Ohm dummy load and wattmeter to
the 144/430 MHz antenna jack
5. Tune the transceiver to 439.995 MHz in the CW mode.
6. Press the PTT, and adjust
VR3003 for minimum indi-
cation on the DC voltmeter.
7. Leave the transceiver on 439.995 MHz band and key
the transceiver.
8. Adjust TC3001 for maximum indication on the watt-
meter.
PA Unit Alignment Points
TP3025
TP3026
VR3003
TC3002
TP3003
TC3001
VR3001