Tait TB7100, Service Manual

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TB7100 Service Manual Transmitter Fault Finding (50W/40W) 341
© Tait Electronics Limited October 2005
Task 35 —
Check Components
of LPF
If there are no faults in the final RF signal path up to and including the PIN
switch, then the fault should lie in the LPF. Check the LPF as follows:
1. If not already done, remove the
LPF TOP
can.
2. Connect the RF connector to the test set.
3. Check the capacitors and inductors of the LPF between the PIN
switch and the RF connector. See
Figure 14.29 . Check for shorts,
open circuits, and faulty components. Repair any fault.
4. In the case of the B1 band, replace the
LPF TOP
can before continuing.
5. Enter the CCTM command 326 5 to set the transmitter power level
to the maximum.
6. Enter the CCTM command 101 x x 0 , where x is the lowest
frequency (in hertz) for maximum power, as given in Table 14.8
(B1 band), Table 14.9 (H5) or Table 14.10 (H7).
7. Enter the CCTM command
33
to place the radio in transmit mode.
8. Measure the RF output power. This should be:
9. Enter the CCTM command
32
to place the radio in receive mode.
10. Enter the CCTM command 101 x x 0 , where x is the highest
frequency (in hertz) for maximum power, as given in Table 14.8
(B1 band), Table 14.9 (H5) or Table 14.10 (H7).
11. Repeat Step 7 to Step 9 .
12. If the power in both the above cases exceeds 70W (B1) or 60 W
(H5, H7), the fault has been rectified; go to
“Final Tasks” on
page 123 . If it does not, the repair failed; replace the main-board
assembly and go to “Final Tasks” on page 123 .
RF output power: more than 70W (B1 band)
more than 60W (H5, H7 bands)