TRANSCEIVER 800 MHz MTP700 Portable Radio / Detailed Service Manual 4.2 - 73
Receiver Troubleshooting
Check Front Gain, using
a RF probe on C540,
frequency 109.65MHz.
Check second LO.
-16dBm<Power<-10dBm
Freq = 219.3MHz
Repair if necessary
(See Synth. Troubleshooting)
Check with all power
Inputs/Outputs of Ant. SW.,
Front Filter (Fl500), LNA
(U500), Second Filter (Fl501),
Mixer (U504), Xtal Fitler
(Fl502). Replace if necessary.
Check Front Gain a
gain.
Is the
gain below
5dB?
Run RX_BER –112dBm &
ULTIMATE_BER
Check Baseband Output at WPIC
(U503) TP600/TP601.
Look for sinewave ‘type’ waveform.
Check 2.775V supply to
LNA & Mixer and check
control line (Q500,Q501).
Repair if necessary.
Check Front Gain again.
Return
to first
TetraCom Commands (TDM Mode):
> Test_Enter
> L1timer on
> Freq Rx 860.0125
> Mode RXTDM
> Mode RSSI
or
>ModeBER
Rout WPIC Baseband signal to test
points:
>WPIC2072NOW
Activating control lines at continuous
mode:
>WPIC391bNOW
CheckMainSynth.Power
level (>-5dBm) and frequency.
(Fmain=Frx+109.65MHz)
Repair if necessary.
(See Synth. Troubleshooting)
Is the
gain still below
5dB?
Was that
the
Problem?
Passed?
Check
WPIC
OK
Is the
gain still below
5dB?
Yes
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
No
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