Motorola CDM Series Basic Service Manual page 56

4-14
Table 4-12: Default Softpot for UHF (450-512 MHz/ 25W - LDMOS)
Perform the front end filter tuning procedure as follows:
1. Under the Rx Align menu, select the Front End Filter option.
2. Select the thumb of the slider of the frequency point given under "Frequency Point" for the radio's
frequency band from one of the Table 4-7 through Table 4-12.
3. Inject a -87dBm RF signal with the frequency selected in Step 2, modulated with 1kHz tone at
60% rated deviation of values listed in Table 4-13. A 1kHz tone must be audible to make sure that
the radio is receiving. Switch off the modulation.
4. Set the softpot to the start value given specified in one of the Table 4-7 through Table 4-12 by
adjusting the slider, keying in the softpot values in the edit box (press ENTER to confirm the
selection) or using the spin control.
5. Measure the RSSI voltage with a DC voltmeter capable of 1mV resolution. It is recommended that
an RCA filter (1.5K-47uF) be added at the input of the voltmeter to reduce RSSI noise. Call this
V1.
6. Change the softpot value by the "Step Value" specified in one of the Table 4-7 through Table 4-12.
A positive step value must be added, while a negative value must be subtracted from the current
softpot value. Call this SP.
7. Re-measure the RSSI voltage. Call this V2.
8. Calculate the RSSI voltage change in percent using the formula 100* (V2/V1-1). If the calculated
value is negative or lower than the target value given from one of the Table 4-7 through Table 4-
12, continue with Step 9. Otherwise repeat Steps 6 through 8.
9. Calculate the softpot offset using formula SP – Default SP. For Default SP, use the default
softpot value specified in Table 4-7 through Table 4-12 for the tuning frequency given in Table 4-
14. Add the calculated offset to all default values given in the table for the radio's frequency range
and enter the results in the edit boxes for the appropriate softpot frequencies.
10. Program the softpot values into the radio by pressing the Program button.
11. Exit the front end filter tuning function.
Frequency Point
F1
F2
F3
F4
F5
F6
F7
Radio Programming and Tuning Procedures
Softpot Value (Decimal)
53
59
65
73
75
79
87