Tait TB7100 Service Manual

TB7100 Service Manual Servicing Procedures 117
© Tait Electronics Limited October 2005
Task 8 —
Check Transmit
Deviation and
Audio Distortion
This task only needs to be carried out if it relates to the fault reported or if
the reported fault is not sufficiently specific to identify the faulty module.
Caution Observe the servicing precautions for the transmit-
ter listed in “Transmitter Issues” on page 81.
1. Connect the audio output from the test set to the Line Input on the
CTU.
2. Set up the modulation analyser in the test set to measure the
distortion and deviation of the modulated audio signal.
3. Set up the test set audio generator output to be 1kHz and at the level
required by the customer’s system to produce 60% full system
deviation (providing this is within the specified limits of the base
station).
4. Activate the T
X KEY switch and verify that the measured deviation is
60% of full system deviation and that the measured distortion level is
within the transmitter specifications as detailed in the specifications
manual.
5. If the measured value agrees with the programmed settings, go to
Step 8, If it does not, attempt to complete the required transmitter
audio level adjustment as described in the installation and operation
manual.
6. If this rectifies the fault, go to Step 8. If it does not, check whether
the SI board and cable or the transmitter module is faulty by
connecting a spare transmitter module.
Tip It is not required to remove the original transmitter board from the
tray chassis. Just unplug the connectors.
7. If this rectifies the fault, the original transmitter module is faulty.
Reconnect the original transmitter module and go to Task 9
.
Then continue with Step 8.
8. Repeat from Step 1 using the Unbalanced Line Input.
9. Connect a fist microphone to the P
ROG/MIC connector, and whistle
into the microphone while pressing the PTT key. Verify whether
close to full system deviation is measured.
Note For a more accurate measurement, the TOPA-SV-024 test unit
can be used to connect the microphone input of the base station
to an audio source.
10. If the deviation is correct, go to Step 12. If there is no deviation or
very low deviation, check whether the UI board and cable or the
transmitter module is faulty by connecting a spare UI board and cables
to both transmitter and receiver.

Tait TB7100 Specifications

General

Brand	Tait
Model	TB7100
Category	Accessories
Language	English