User's Manual

14221-1200-4010, Rev. B

17.5 LOW BAND PA TRANSMITTING INTO ITS ANTENNA

1. To verify transmit output power of the LBPA, perform the test procedure presented in the previous

section (Section 17.4).

2. Disconnect the 50-ohm load/terminator from the wattmeter.

3. Connect the cable from the vehicle-mounted LBPA antenna (cable labeled “LBPA Antenna”) to the

wattmeter’s output connector. See Figure 17-2.

4. Insert a 5-watt element into the wattmeter and position the element to measure forward RF output

power. Rotate it as necessary. The arrow on the face of the element must point away from the LBPA

and towards the antenna for forward power measurements.

5. Insert the 20 dB attenuator between the LBPA and the Wattmeter.

6. Set the wattmeter to measure peak RF power.

7. Turn on the XG-100M mobile radio, if not already on, via the control head’s on/off volume control

(or externally-mounted switch).

When the LBPA begins transmitting, an antenna must be connected and personnel

should be at least the minimum safe distance from the antenna. Minimum safe

distances from the LBPA antenna are listed in Table 1-1 on page 9.

8. Compare the wattmeter’s reading with the target RF output power range of between 0.9

and 1.2 watts (100 watts ±1 dB).

This transmit output power range assumes the LBPA is currently configured for maximum transmit

power. The LBPA may be configured with a lower RF output power per the MRU configuration.

For the LBPA, because a 20 dB RF attenuator used, any measurement from the wattmeter

must be multiplied by 100 to obtain the radio’s actual output power in watts.

9. If the wattmeter reading is within the range, record the value in the appropriate space on the data

collection form near the end of this manual (page 90).

If the wattmeter reading is outside the range, first verify the LBPA antenna’s driven element is

properly trimmed. Before making any antenna adjustments, be sure to disable the LBPA to stop

transmitting.

Verify LBPA power source voltage (i.e., battery voltage) is within the specified range, recheck all

connections, and measure the forward power again. If this fails to produce a reading within the range,

check all cabling and connections, and repeat the testing procedure to this point. In the event the

wattmeter reading still falls outside the range, replace the antenna, make sure all connections are

seated firmly, and repeat the testing procedure. If problems persist, contact the Technical Assistance

Center (see page see page 21).

10. Turn off the MRU. The LBPA should stop transmitting immediately, as indicated by the wattmeter.

NOTE