4-8 Radio Programming and Tuning Procedures
4.4.6 Modulation Balance Attenuation
Perform the modulation balance attenuation procedure as follows:
1. Under the Tx Align menu, select Mod Balance Attn.
2. Begin with the lowest frequency, i.e., the first frequency point from the top. Press PTT Toggle
without selecting any slider control at the corresponding frequency point. This keys the radio up at
the first frequency point.
3. Inject 80 Hz at 100mVrms.
4. Record the deviation obtained. Typical values should range from 3.5-5.5 kHz.
5. Inject 3 kHz at 100mVrms.
6. Change the modulation balance attenuation setting until the Tx deviation is as recorded in Step 4.
7. Inject 80 Hz at 100mVrms, and check the deviation again. If Tx deviation changes, note the read-
ing and repeat Steps 5, 6, and 7 until the Tx deviation remains the same.
8. Press PTT Toggle to dekey the radio. Choose the next frequency, key up, then repeat Steps 3 to
7 until all seven tuning points are completed.
9. Program the softpot value by pressing the Program button.
10. Exit the modulation balance function.
Note:
1. When using test box RLN4460B/C, inject the signal into the radio at the METER IN
terminal and set the METER IN selector switch to “VOL”.
2. Tuning of the transmit power and reference oscillator warp must be performed
first.
3. This tuning method is performed for multiple Modulation Balance Attenuation
Tuning Channels.
4. Compensation alignment balances the modulation sensitivity of the VCO and ref-
erence modulation (synthesizer low frequency port) lines. The compensation
algorithm is critical to the operation of signaling schemes that have very low fre-
quency components (i.e. DPL) and could result in distorted waveforms, If not
adjusted properly.
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