Motorola VRS750, Service Manual

Page: 26 / 104

14
Once the setup is complete and the mobile is turned on the current
tuning parameters can be read from the VRS750 by selecting
File -->
Read Radio Information and Softpots on the Global Tuner.
NOTE: Radio Serial Number and Radio Model Number shown
at the bottom of the screen will not match the model
number and serial number of its associating VRS.
Transmit Power Tuning
The VRS750 supports 2 different power levels (High and Low). There
are separate alignments for High and Low power (see Tables 2 and 3).
We recommend setting and using a
Low transmit power setting of
275 mW for optimal performance. This output power provides the
VRS750 with a similar range as the portable when attached to a mobile
antenna. Any deviation from this setting could result in a loss of
communication from the portable to the base.
NOTE: Please also note that some countries may have
different restrictions on the power level. If you are not
sure on the power to tune, please check with your
regulatory body. The maximum available power level
given in the table below must not be exceeded.
NOTE: When checking the RF power output of the VRS750,
always use an attenuator pad of at least 30 dB attached
to the radio end of the RF cable. This will avoid an RF
mismatch and ensure a stable RF reading that will not
change with varying lengths of connecting cable.
NOTE: The VRS750 will be programmed from the factory with
a high power setting of ~2 W and a low power setting
of ~275 mW.
To perform Transmit High Power Tuning, do the following:
1. Under the Tx Align menu, select Transmit Power , then select
High (see Figure 14).
2. Press PTT Toggle . This will key the radio up at F1.
3. Adjust the high power level by moving the slider/spin control or
keying in values in the edit control (press ENTER to confirm
selection after typing in the softpot value).
4. Press PTT Toggle to dekey the radio, go to the next frequency
point by selecting the slider, typing in the edit control box (press
ENTER to confirm selection after typing in the softpot value) or
toggling the softpot value using the spin control.
Table 2. Transmit High Power Level for VRS750s
RF Band (MHz) High Power (W)
VHF (136-174) 5.2-5.7
UHF Band 1 (403-470) 4.2-4.6
UHF Band 2 (450-527) 4.2-4.5