LG 512W, Service Manual

Page: 59 / 104

B. Transmitted RF Level and Checks
This section shows the typical RF levels expected throughout the transmitter path. A block diagram
showing the locations of the RF measurement points and levels is shown in Fig. 5-7.
• Transmitter Testing Set-up
To check the transmitter the following conditions have to be set:
1. Set the DC Power supply to 4.0 V.
2. Power up the GSM/DCS test set and then establishing a call with an attached mobile on active
mode.
3. Select Channel, TX Level and Input Level according to which parameter is required.
Note: All RF values shown are only intended as a guide figure and may differ from readings taken
with other test equipment and leads. Lead and connector losses should always be taken into
account when performing such RF measurements.
• Testing Transmitter
Using a suitable high frequency probe measure the RF levels at the relevant points shown in Fig.
5-4, 5 and compare your measurements with those shown in the diagram. If there are any major
difference between the readings taken and those indicated then further investigation of that
particular point will be required. It will also be necessary to ensure that all the following power
supplies and signals are present which control this part of the transmitter circuit:
1. The Control Signal of FEM (see Fig. 5-13, 14, 15)
2. RF2V8 (see Fig. 5-10)
3. 2V7_VTCXO (see Fig. 5-11)
4. 13 MHz (see Fig. 5-12)
5. TXEN, TXRAMP, TXPA (see Fig. 5-19)
6. TX IP, IN, QP, QN (see Fig. 5-20)
5. TEST POINT DATA
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