Tait TM8235, Service Manual

Page: 303 / 578

TM8100/TM8200 Service Manual Transmitter Fault Finding (40W/50W) 303
© Tait Electronics Limited June 2006
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), 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 11.17 ). 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 (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 11.17 ) . If C3500 is not faulty, go to
“Frequency Synthesizer Fault Finding” on page 179 . If C3500 is
faulty, replace it and return to Step 2 .