MX800 Transceiver Technical Manual
© SPECTRA ENGINEERING 2006 Revision 4.2.3
78
Procedure:
1. Disable the CTCSS if present. This is either done through the digital
input port at the rear or temporarily disabling it in the Channel
Information Screen.
2. PTT transmitter.
3. Set the transmitter modulation frequency to 1kHz, +10dBm injected in
through the WB/ DCFM input, CN1 pin13 with JMP8 set to 1-2. Note
that signals injected into this port must be A/C coupled (1UF cap) as this
point is biased at 2.5VDC.
4. Adjust the VCO Deviation digital potentiometer using MXTOOLS until
the correct deviation is obtained. (See Table 5-1 Peak Deviation
Settings).
5. Set the transmitter modulation frequency to 400Hz, +10dBm, injected in
through the WB/ DCFM input.
6. Adjust the Reference Deviation digital potentiometer until the top of the
waveform is flat. If the waveform top droops increase the level (see
Figure 5-1) and if it peaks reduce the level (see Figure 5-2).
7. Repeat steps 3 through to 6 until the correct peak deviation and
modulation balance is obtained.
Examples of incorrect, observed waveforms are as follows:
Figure 5-1 Under (increase level) Figure 5-2 Over (decrease level)
The waveform when correctly aligned should look as follows:
Figure 5-3 Correctly Aligned Waveform
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