MXi005U OPERATIONS AND MAINTENANCE
3.3
3.4
3.4.1
B
EFORE
T
URNING THE
A
MPLIFIER
ON
Check that all of the following conditions are met:
1. Modulator
is
Ready.
•
Usually in the application of AC, the Modulator goes through its warm-up sequence. Ensure that it has
done so.
2. MXi CONTROLLER is ready.
•
If there were prior faults, clear them by pushing the RESET button.
3. INTERLOCKS are closed or OK.
•
Interlocks and Status are OK.
4. The TX is OFF.
•
Push the Front Panel ON/OFF button so that it is NOT pushed in.
5. The Fan is working.
•
As soon as AC is applied to the amplifier the Fan should startup.
A
MPLIFIER
ON
S
EQUENCE
Upon depressing the ON button, the +28V power supply is enabled, thus applying B+ to the MXi Amplifier. Since
the Modulator is on hot standby (RF is always applied), the amplifier normally produces output power
immediately.
Turning ON MXi Amplifier
6. Push the front panel ON button. The MXi Amplifier should now be ON.
7. Monitor the +28V power supply voltage and current on the LCD screen. With the user interface program
check that the power supply is operating by observing the voltage and power supply status indicator. The
voltage reading should be about 28V and the power supply status indicator should be green.
ALLOW THE AMPLIFIER SOME WARM-UP TIME!
Only after the transmitter has been ON for approximately 15 minutes should you perform fine adjustments.
The amplifier must be allowed to reach its operating temperature for stable and consistent operation. The
Power Amplifier in the MXi transmitter is equipped with thermal compensation circuits, which reduce the
output power when the temperature rises. Therefore, the operating temperature must be reached before
adjusting the RF level to its proper level. The amplifier is also equipped with Automatic Gain Control, primarily
designed to prevent the transmitter from overpower or overdrive condition.
8. Increase the RF output by slowly adjusting the Modulator output level control. Increase the power to 100%. At
this time the proper warm-up period begins.
9. With the amplifier fully functional and adjusted to its final setting, record keeping becomes very important.
Record the current, voltage, power, etc. This data can be used as a very valuable troubleshooting tool later.
Below is typical test data pertaining to the MXi amplifier at 100% output power.
TYPICAL DATA read on the User Interface Program
FWD
100%
RFL
00.1%
AGC
1.0V
CUTB
0.1V
PS
VOLTS
28.0V
PUB06-76 Rev 2 July 18, 2007
06-76-9
MXi005U Operations and Maintenance
