Motorola APX 6000 Service Manual

5-44 Troubleshooting Charts: RX RF Failure
RX RF Failure – Page 10
Check Mixer:
Remove shield, SH5A. Check the
polarity of T503 and check to
see that all pins are grounded.
Visually inspect windings.
Is the polarity
correct and all pins
are gounded?
13
Measure the LO power going into the mixer, U506,
For VHF & 7/800 radio, at the output side of C599.
For UHF1 radio, at the output side of C528.
Is the LO power
= -5 dBm?
Testing a UHF radio?
Remove shield, SH2. Check
the polarity of T504 and check
to see that all pins are
grounded. Visually inspect
windings.
Is the polarity
correct and all pins
are gounded?
Is the polarity
correct and all pins
are gounded and the
windings look ok?
Replace
T503
Check FGU and
replace U506 if
needed.
Check FGU and
replace U506 if
needed.
Replace
T504
No
Yes
Yes
Remove shield, SH7. Check
the polarity of T505 and check
to see that all pins are
grounded. Visually inspect
windings.
Yes
No
No
Replace
T505
No
No
14
Remove shields, SH2 &
SH5C. Measure IF level at
XTAL filter and compute
XTAL filter loss, non
ground side of C515 and
non ground side of C516.
Loss:
VHF: < 3 dB?
700: < 4 dB?
800: < 3 dB?
UHF1: < 3 dB?
UHF2: < 3 dB?
Measure RF levels at IF
Amplifier and compute
gain, input side of C519
& output side of R511.
Gain approximately 12dB?
No problem
found.
12
No
Yes
Check LNA:
Check DC bias voltages
of Q503 at the base (pin
1) & collector (pin 3).
Is base voltage =
0.756 V?and
collector voltage =
1.560 V?
Check DC bias voltages of
Q501at the base (pin 2 or
5), collector (pin 3) and the
emitter (pin 4).
Is base voltage =
1.080 V? Collector
voltage = 0.756 V?
Emitter voltage = 1.583 V?
Check DC input line voltages
and visually inspect and
replace defective
components if needed.
No
Yes
No
Yes
Replace
Q503
Replace
Q501
Yes
No
14
Yes
Yes
Note: RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075 MHz
700: 769.0625MHz
800: 860.0625MHz
Measured with a high impedance probe for
relative comparisons and troubleshooting only.
Actual S21 gain or loss may differ if the
test point is not 50 ohms.

Motorola APX 6000 Specifications

General

Frequency Range	700/800 MHz, VHF, UHF Range 1, UHF Range 2
IP Rating	IP67
P25 Phase 1 & 2	Yes
GPS	Yes
Encryption	AES, DES
Power Output	1-3 Watts (700/800 MHz)
Operating Temperature	-30°C to +60°C
Intrinsically Safe	Yes
Bluetooth	Yes (Bluetooth 4.0)