Icom IC-756PRO - 4-3 RECEIVER ADJUSTMENTS

4 - 6
*This output level of a standard signal generator (SSG) is indicated as SSG’s open circuit.
RECEIVER ADJUSTMENTS—continued
RECEIVER
TOTAL GAIN
NOISE
BLANKER
SPECTRUM
SCOPE
ADJUSTMENT
ADJUSTMENT ADJUSTMENT CONDITION
MEASUREMENT
VALUE
POINT
UNIT LOCATION UNIT ADJUST
1
2
1
2
1
2
3
• Display frequency: 14.100000 MHz
• Mode : USB
• Filter : 2.4 kHz
• [P.AMP] : OFF
• Connect an SSG to [ANT1] connec-
tor and set as :
Frequency : 14.101500 MHz
Level : 500 µV* (–53 dBm)
Modulation: OFF
• Receiving
• Set an SSG output level to OFF.
• Receiving
• Display frequency: 14.100000 MHz
• Mode : USB
• [P.AMP] : P.AMP1
• [NB] : OFF
• Connect an SSG to [ANT1] con-
nector and set as :
Frequency : 14.101500 MHz
Level : 10 µV* (–87 dBm)
Modulation: OFF
and apply following signal to [ANT1]
connector.
• Preset R271 on the MAIN unit to
the 12 o’clock position.
• Receiving
• [NB] : ON
• Receiving
• Display frequency: 14.100000 MHz
• Mode : USB
• [DUAL WATCH] : OFF
• [P.AMP] : OFF
• [SCOPE] : ON
• [SCOPE ATT] : OFF
• Verify the connection of J841 on the
RF unit and P801 (S3LO: 12.89000
MHz/–7 dBm) from the PLL unit.
• Connect an SSG to [ANT1] con-
nector and set as :
Frequency : 14.101500 MHz
Level : 1 µV* (–107 dBm)
Modulation: OFF
• Receiving
• Set an SSG output level to OFF.
• Receiving
• Set an SSG output level as:
Level : 50 mV* (–13 dBm)
• Receiving
Rear
panel
MAIN
RF
Connect an AC milli-
volt meter to [EXT
SP] connector with
an 8 Ω load.
Connect an oscillo-
scope to check point
CP271.
Connect a digital
multimeter oroscillo-
scope to check point
CP871.
1.0 V (0 dB)
32 mV (–30 dB)
Maximum noise level
At the point where the
voltage just reduces.
Muximum voltage
0.05 V–0.15 V
4.35 V– 4.45 V
Front
unit
MAIN
MAIN
RF
[AF]
control
R210
L271,
L272
R271
L812,
L813,
L833
R872
R863
100 msec.
1 msec.