Codan 2110 series, Руководство по ремонту, Страница: 98 / 164

Repair procedures, tests, and adjustments
66 Manpack Transceiver 2110 series Repair Guide
1
While viewing the tone on the oscilloscope, use the volume control on the front
panel to increase the audio level to full volume.
1
Record your results and actions (see page 109, Test sheet for the 2110 series
Manpack Transceiver ).
1
Switch off the RF output from the RF signal generator.
1
Switch the 0208 speaker to
Speaker
.
1
Replace the oscilloscope with an AC voltmeter.
1
Return to the Repair flowchart (see Figure 29 on page 95 ).
Performing the Selectivity test
To test the selectivity of the transceiver:
1
Set up the equipment (see page 56, Setting up the test equipment ).
1
Select a channel to test, preferably near the centre of one of the designated bands
(see
page 60, Examining the profile in the transceiver ).
1
Set the RF signal generator to 1.0 kHz above the SCF of the selected USB channel
or 1.0 kHz below the SCF of the selected LSB channel.
1
Set the RF output level of the RF signal generator to –120 dBm.
1
Switch on the RF output from the RF signal generator.
1
Adjust the volume via the front panel to full volume.
1
Set the 0 dB reference on the AC voltmeter to the level of the tone (approximately
–16 dBm).
1
Set the RF signal generator to 1.0 kHz below the SCF of the selected USB channel
or 1.0 kHz above the SCF of the selected LSB channel.
1
Increase the RF output level of the RF signal generator to –55 dBm.
1
Record your results and actions (see page 109, Test sheet for the 2110 series
Manpack Transceiver ).
Pass A waveform that does not clip, and reaches a maximum of
1.0 V p–p.
NOTE
The receive audio output from the 0208 is half that of the speaker on
the 2110, that is, the audio output from the 2110 should reach
approximately 2 V p–p at full volume.
NOTE
The setting varies slightly depending on the selected channel with
respect to its positioning along the filter band and the noise from the
RF signal generator.
Pass A reading on the AC voltmeter that is < 0 dB.