TA2922 TM8/TM9 Universal Line Interface Board Installation Instructions 7
© Tait Electronics Limited April 2010
Setting line output level (VR1)
13 Connect the radio to the instruments as shown in the diagram.
14 Set the radio communications analyser to generate an on-signal frequency at a level of
-70dBm. Modulate with a 1kHz tone at a level of 60% system deviation (1.5kHz for
narrow band, 3kHz for wide band).
15 Ensure there is a 600 ohm termination resistor fitted across the two balanced line out
audio wires.
16 Monitor the audio level using the communications analyser and adjust RV1 on the
TA2922 interface to achieve the desired output level.
Setting line input level (VR2)
17 Connect the radio to the instruments as shown in the diagram.
18 Set the radio communications analyser to monitor the radios RF transmission.
19 Set the audio generator to produce a 1kHz audio tone at the desired level.
20 Activate the TX key input to the TA2922 interface to set the radio to transmit.
21 Monitor the transmitter deviation using the communications analyser and adjust RV2
on the TA2922 interface to achieve 60% system deviation (1.5kHz for narrow band,
3kHz for wide band).
Setting talk-through level (VR3)
Important: This feature cannot be used when the TA2922 is operating in 2-wire mode as
it may cause audio oscillations or instability.
22 Fit VR3 (IPN 040-06000-00) to the TA2922 interface by soldering in the three com-
ponent leads.
23 Align both the line in and line out audio levels as described in the previous section.
24 Disable the RF output of the communications analyser so that the radio is in an idle
state (not transmitting and not receiving a RF signal).
25 On the communications analyser, generate a 1kHz tone at the nominal audio level,
connect this to the TA2922 line input.
26 Ensure there is a 600 ohm termination resistor fitted across the two balanced line out
audio wires.
27 While continuing to generate the 1kHz tone, monitor the TA2922 line output on the
communications analyser.
28 Adjust VR3 on the TA2922 line interface to set the desired talk through audio level.
29 Refit the radio lid and top cover to the radio.
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