Poor Rx Sensitivity Or No Rx Audio (700-800 Mhz)-Part 1 Of 2 - Motorola ASTRO XTL 1500 Detailed Service Manual

Digtal, vhf/uhf range 1/uhf range 2/700–800 mhz

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5.6.33 Poor RX Sensitivity or No RX Audio (700–800 MHz)—Part 1 of 2

Sensitivity or no

Measure Transceiver

Sinad by injection

signal at antenna port

< - 119.1dBm?

Check RF level at

Mixer LO injection port

(U6251 Pin 3 side 1)

Check RX front-end

filter switching

voltage Table

Figure 5-33. Poor RX Sensitivity or No RX Audio (700–800 MHz)—Part 1 of 2

June 15, 2005

3kHz FM Deviation

1kHz Audio tone

Check Receiver

VCO troubleshooting

(LO injection section)

Check Q6350,

Q6251, Q6252,

Q6253, Q6254

and make any

necessary repairs

Troubleshooting Charts: Flowcharts

RX Switching Voltages

Receiving at

MAEPF-27875-O

Receiving at

6815854H01-A

Troubleshooting