User Manual

14221-1200-4000, Rev. A
82
14.3 TRANSMITTING INTO THE MOBILE ANTENNA—TESTING THE
ANTENNA SYSTEM
1. Connect the antenna cable from the vehicle-mounted antenna to the wattmeter as shown in Figure
14-1.
2. Turn the radio on and set it to a VHF P25 conventional channel allocated for radio testing. This
should be the same channel that was used during the previous test procedure.
When transmitting into an antenna, always observe the RF exposure-related
safety information presented in Section 1.2 (begins on page 6).
3. Position the wattmeter’s slug to measure forward RF output power. Rotate it if necessary. The arrow
on the face of the slug must point away from the radio and towards the antenna for forward power
measurements.
4. Set the wattmeter to measure peak RF power.
5. Key the radio’s transmitter via the microphone’s PTT button.
6. For a VHF or a UHF band transmission, compare the wattmeter’s reading with the target RF output
power range of between 39.8 and 63 watts (50 watts ±1 dB). This transmit output power range
assumes the radio is currently configured for high-power transmit.
For a 700 MHz band transmission, compare the wattmeter’s reading with the target RF output power
range of between 19.8 and 31.4 watts (25 watts ±1 dB). This transmit output power range assumes
the radio is currently configured for high-power transmit.
For an 800 MHz band transmission, compare the wattmeter’s reading with the target RF output power
range of between 27.8 and 44.1 watts (35 watts ±1 dB). This transmit output power range assumes
the radio is currently configured for high-power transmit.
Transmit only for as long as needed to take the measurement, then immediately
disable the transmission.
For 700 MHz band transmissions, if an interoperability channel is selected, the radio
will only transmit with approximately 2 watts of RF output power.
7. 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.
If the wattmeter reading is outside the range, verify the radio’s power supply voltage (i.e., battery
voltage) is within the specified range, recheck all connections, and measure the forward power again.
If these checks/corrections fail 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 21).
8. Position the wattmeter’s slug to measure reverse (reflected) RF power from the antenna. The arrow
on the face of the slug must point away from the antenna and to the radio to measure reverse power.
9. Key the radio’s transmitter via the microphone’s PTT button.
CAUTION
NOTE
NOTE