Motorola SSETM 5000 service manual Transmitter Alignments, Softpot, Reference Oscillator Alignment

Radio Alignment Procedures: Transmitter Alignments 5-3

5.5Transmitter Alignments

5.5.1Softpot

The alignment screens introduce the concept of the “softpot,” an analog SOFTware-controlled POTentiometer used for adjusting all transceiver alignment controls.

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C a u t i o n

DO NOT switch radios in the middle of any alignment procedure. Always left-click the Close button on the screen to return to the Main Menu screen before disconnecting the radio. Improper exits from the alignment screens might leave the radio in an improperly configured state and result in seriously degraded radio or system performance.

Each alignment screen provides the ability to increase or decrease the softpot value by using a slider or the spin buttons in the New Softpot Value box, or by entering the new value from the keyboard directly into the box. The slider bar indicates the minimum and maximum values of the softpot, while the Radio Softpot Value indicates the recommended value; see Figure 5-4.

Figure 5-4. Typical Softpot Screen

Adjusting the softpot value sends information to the radio to increase (or decrease) the voltage in the corresponding circuit. For example, left-clicking the UP spin button in the New Softpot Value scroll box on the Reference Oscillator screen instructs the radio’s microcomputer to increase the voltage across a varactor in the reference oscillator, which increases the frequency.

In ALL cases, the softpot value is just a relative number corresponding to a digital-to-analog (D/A) generated voltage in the radio.

Perform the following procedures in the sequence indicated.

NOTE: Some of the following screens may vary depending upon the radio under test and the version of tuner software you are using. Refer to the software’s online help.

!When keying the radio during a test, always transmit into a dummy load.

C a u t i o n

5.5.2Reference Oscillator Alignment

Adjustment of the reference oscillator is critical for proper radio operation. Improper adjustment will result not only in poor operation, but also in a misaligned radio that will interfere with other users operating on adjacent channels. For this reason, the reference oscillator should be checked every time the radio is serviced, or once a year, whichever comes first. The frequency counter used for this procedure must have a stability of 0.1 ppm (or better).

6881094C12-A November 11, 2004