132 Servicing Procedures TP9100 Service Manual
© Tait Electronics Limited May 2005
Task 9 —
Check the Transmit
and Transmit-Audio
Functions
If the radio does not transmit, this can be caused by:
■ the synthesizer not being in lock
■ no or wrong carrier power
■ a faulty speaker (which also serves as the microphone)
■ no modulation
If the cause is already known, go directly to the relevant fault-finding
section.
Caution Observe the servicing precautions for transmitter
issues listed on page 85.
1. Use CCTM command 101 x y 0 to set the transmit frequency to the
bottom of the band.
2. Use CCTM command 33 to set the radio to transmit mode.
3. Use CCTM command 72 to read the lock status.
Note The last value returned (LO2) does not have to be in lock while
transmitting.
4. If the synthesizer is in lock, go to Step 5. If the synthesizer is not in
lock (one or both of the first two values returned are “0”), repair the
radio as described in “Frequency Synthesizer Fault Finding” on
page 159.
5. Repeat Step 1 to Step 4 with the transmit frequency set to the top of
the band.
6. Use CCTM command 326 1 to set the power level to very low.
7. Connect a power meter and measure the transmit power.
8. If the carrier power is correct, go to Step 10. If the carrier power is
not correct, try to re-calibrate the radio.
9. If the re-calibration repairs the fault, go to “Final Tasks” on page 134.
If it does not, repair the radio as described in “Transmitter
Fault Finding” on page 217.
10. Repeat Step 6 to Step 9 with the power level set to high (326 4).
11. Check whether the speaker/microphone is the source of the fault, as
described in “Internal Speaker/ Microphone Faulty” on page 146.
12. If the radio transmits audio now, the original speaker was faulty.
Reassemble the radio and go to “Final Tasks” on page 134. If the
radio still fails to transmit, reconnect the original speaker and go to
Step 13.
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