Tait TM8100 mobiles - Page 316

316 Transmitter Fault Finding (>25W) TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
Task 2 6 —
Output of
Frequency
Synthesizer
The first point to check in the initial RF signal path is the output SYN TX LO
from the frequency synthesizer. This signal is input to the exciter at C300.
1. For test purposes select a representative power level and frequency
from Table 11.8 (B1), Table 11.9 (G2), Table 11.10 (H5) or
Table 11.11 (H7). (Note that the data for these tables were obtained
using an RFP5401A RF probe.)
2. To set the power level, enter the CCTM command 326 x, where x
defines the level. To set the frequency, enter the CCTM command
101 x x 0, where x is the frequency in hertz.
3. Enter the CCTM command 33 to place the radio in transmit mode.
4. Use an RFP5401A RF probe or the equivalent to measure the RF
voltage after C3500 (see Figure 11.21). Earth the probe to the
FCL TOP can adjacent to the PA driver circuitry. The required voltage
should be as given in Table 11.8 (B1), Table 11.9 (G2),
Table 11.10 (H5) or Table 11.11 (H7).
5. Enter the CCTM command 32 to place the radio in receive mode.
6. If the voltage measured above is correct, go to Tas k 27
. If it is not, go
to Step 7.
7. Check C3500 for VHF and UHF (see Figure 11.21) or C300 for
the K5 band (see Figure 11.22). If this component is not faulty, go
to “Frequency Synthesizer Fault Finding” on page 185. If this
component is faulty, replace it and return to Step 2.