Tait T830 Series, Руководство по обслуживанию

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31/01/96 Copyright TEL
Reset RV202 fully clockwise.
Connect the key line to earth, then disconnect, ensuring that the T836/837 turns
off immediately the key line is broken.
Set RV202 for the required tail time.
4.5 Transmit Timer
Ensure that R257 is in circuit.
Adjust RV201 fully anticlockwise.
Earth the key line.
Check that the T836/837 turns off after approximately 1 minute.
Adjust RV201 fully clockwise.
Open and then earth the key line.
Check that the T836/837 turns off after approximately 3 minutes.
Set RV201 for the required transmit time.
4.6 Frequency Response
If the T836/837 has been correctly adjusted, the pre-emphasis and limiting responses
should closely match those shown in Figure 4.1 and Figure 4.2 respectively.
Note 1: The limits shown on these graphs should not be exceeded.
Note 2: The curves are shown for wide band sets.
• Measure the pre-emphasis response as follows:
Reduce the line level to give 1kHz [0.5kHz] deviation at 1kHz.
Sweep the modulation frequency.
The response should closely match that shown in Figure 4.1.
• Measure the limiting response as follows:
Set the line level to give 3kHz [1.5kHz] deviation at 1kHz.
Increase the line level 20dB and sweep the modulation frequency.
The response should closely match that shown in Figure 4.2.