Larcan Inc MXI1503U Manual Do Utilizador
MXI1503-2004 OPERATIONS AND MAINTENANCE
PUB13-10 Rev 1
9
2. Monitor the +50V power supply voltage and currents on the LCD. Check that the power supplies are operating
by pressing the P/S touch button. The voltage readings should be about 50V and the currents should be about
45-50 Amps per module under full power.
45-50 Amps per module under full power.
ALLOW THE AMPLIFIER SOME WARM-UP TIME!
Only after the transmitter has been ON for approximately 15 minutes should you perform the fine
adjustments. The amplifiers must be allowed to reach their operating temperature for stable operation. The
Power Amplifiers in the MXi transmitter are 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, i.e. 100%. The amplifiers are also equipped with Automatic Gain
Control, primarily designed to prevent the transmitter from overpower or overdrive condition.
adjustments. The amplifiers must be allowed to reach their operating temperature for stable operation. The
Power Amplifiers in the MXi transmitter are 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, i.e. 100%. The amplifiers are also equipped with Automatic Gain
Control, primarily designed to prevent the transmitter from overpower or overdrive condition.
3. Increase the RF output by slowly turning the Modulator/Exciter or Channel Processor output level control.
Stop at about 25% output power indicated on the LCD. At this level, the current should be around than 20
Amps per amplifier. Current will vary with channel.
Amps per amplifier. Current will vary with channel.
4. If the current is not drastically higher, increase the power to 50%. Again, make note of the PS current
readings. The current should be around 26 Amps per amplifier. Proceed to the next step if this condition is
met.
met.
5. Increase the RF output to 100%. The current should be about 45A-50A per amplifier normal video signal.
6. AGC SETTING: The AGC is setup at the factory for each amplifier. You can raise and lower the AGC level
on the touchscreen under the Comb (combined) submenu. When you select the button to raise or lower the
AGC a command is sent to each amplifier to raise or lower the level the same amount.
AGC a command is sent to each amplifier to raise or lower the level the same amount.
Figure 6 AGC Adjustment
The AGC setup of each amplifier should not be adjusted under normal operating conditions. It should only be
change if you are changing channels. For instructions on AGC setup of the amplifiers see Section 6.1.5
change if you are changing channels. For instructions on AGC setup of the amplifiers see Section 6.1.5
7. With the amplifiers fully functional and adjusted to final settings, 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 Revive amplifiers at 100% output power.
Below is typical test data pertaining to the Revive amplifiers at 100% output power.
5.4.2 TYPICAL DATA read on the LCD
Combined
COMB 100%
AMP1 100%
AMP3 100%
RFL
0.5%
AMP2 100%
AMP4 100% (In the case of a MXi2004)
Amplifier
FWD
100%
RFL
1.0%
AGC
1.0V
CUTB
0.0V
Power Supply
PS VOLTS
50.0V
PS CURR
47A