TM9100 Service Manual Transmitter Fault Finding (50W/40W Radios) 293
© Tait Electronics Limited August 2005
Task 26 —
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 band), Table 11.9 (H5) or Table 11.10 (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 and Figure 11.22). 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 band),
Table 11.9 (H5) or Table 11.10 (H7).
5. Enter the CCTM command 32 to place the radio in receive mode.
6. If the voltage measured above is correct, go to Task 27
. If it is not, go
to Step 7.
7. Check C3500 (see Figure 11.21 and Figure 11.22). If C3500 is not
faulty, go to “Frequency Synthesizer Fault Finding” on page 169.
If C3500 is faulty, replace it and return to Step 2.
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