TECHNICAL NOTE – OPERATION OF MT4400 TWTA
08/10/2004
TN4400-3
MCL, INC.
32 of 36
5.2
Operating Caution List
The table below is a list of improper operating conditions. These are conditions which could
damage the TWT amplifier system and must be avoided. Also listed are the probable sources
of each condition.
SYMPTOM
ORIGIN
Excessive Tube Drive Power
Overdrive on RF System Input or TWTA Gain
Adjustment Set Incorrectly.
Tube or PS Temperature Fault/Alarms
System operation with blocked air intake and/or
exhaust ports.
Excessive Output Reflected Power
Meter Indication
a.
System Output Transmission Line
Connection and Customer Waveguide/Load
Incompatibility.
b. Operating TWTA with unterminated RF
input or output ports.
Failure to avoid the above conditions will void warranties!!
Any of these conditions indicate that a critical system parameter is either out of adjustment or
the fault conditions are no longer recognizable. If these conditions should exist, no further
attempt should be made to use the amplifier system until the defective circuitry or adjustment is
corrected. Of most concern to the operator is potential damage to the TWTA tube because of
its cost and the down time required for repair and/or replacement; therefore, any parameter
relating to the TWTA tube should be analyzed immediately to prevent damage.
5.3
Power-Up Procedure – Remote Panel Usage
When the Initial Turn On check list has been completed and the caution list reviewed, the
system is ready for activation. To activate the system the following steps should be followed:
1.
Activate the HPA Main Power circuit breaker. The HPA Status LED will illuminate.
2.
Verify that the HPA is in the filament delay and will not go into Transmit without
operator interaction. Check that Delay is indicated by the Status LED flashing Yellow.
3.
Send an RF Inhibit Command.
4.
Set the attenuation level to 32.0 dB.
Table 5 – Improper Operating Conditions
CAUTION
