TECHNICAL NOTE – OPERATION OF MT4000 TWTA
10/24/03
TN4000-3
MCL, INC.
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4.2.2 Filament
Delay
This state occurs after a Standby command (Local, Remote, or Computer) has been issued.
During this state all TWTA circuitry will be activated except the high voltage power supply. At
the end of this delay the TWTA will be in the Standby mode.
4.2.3 Standby
This state occurs after the filament warm-up delay has ended or after a Standby command (Local,
Remote, or Computer) has been issued while the TWTA was in Transmit. During this state all
TWTA circuitry will be activated except the high voltage power supply. The Transmit & Standby
modes are mutually exclusive states.
4.2.4 Transmit
This state occurs after a Transmit command (Local, Remote, or Computer) has been issued when
the TWTA was in the Standby mode. During this state all TWTA circuitry will be activated
including the high voltage power supply. The Transmit & Standby modes are mutually exclusive
states.
4.2.5 Transmit
Selected
There are three ways Transmit Selected can be activated. First, when the HPA was in the
Transmit mode then the HPA has a power failure, and then the HPA power returns. After the
power failure, Transmit selected will be activated during filament delay if no faults are present
during delay. Second, while the HPA is in the Delay or Filament Off mode if the operator were to
press the Transmit button, Transmit Selected mode would be activated and at the end of filament
warm-up delay the HPA will go into Transmit. Third, during a tube fault counter cycle. Transmit
selected is a warning to the operator that the TWTA will automatically go into Transmit soon. If
the Standby button is pressed the Transmit Selected mode will be canceled. Transmit Selected
will be indicated in two ways on the local panel during the proportional delay. First an indication
will appear on the front panel vacuum fluorescent display. Second, the Transmit LED located on
the Transmit button will flash.
4.3
RF On/Off Control
The RF On & RF Off modes are mutually exclusive. The HPA status indicator will indicate the
state of the SSA RF switch.
4.3.1 RF Off State
While the HPA is in the RF Off mode the SSA module RF switch will be in the RF Off state.
Any of the following sources may cause an RF Off state and override all other RF On controls.
Each source will be latched and must be returned to the RF On state to clear the RF Off state.
