2-6 Installation XT-50, XT-80, and XT-100 Amplifiers
Control Interface
There are five control inputs as follows:
• AC Power ON (Pin a). Connect Pin a to ground (Pin Z) to enable operation
of the TWTA and turn the TWT's heater on.
• High Voltage ON (Pin F). Connect Pin F to ground (Pin W) to turn high
voltage on.
• Heater Standby (Pin J). Connect Pin J to ground (Pin W) to reduce the
voltage applied to the TWT's heater. This feature is provided to extend the
life of the TWT when the amplifier is the back-up unit in a redundant
configuration. The High Voltage ON overrides the Heater Standby
command and returns the TWT's heater voltage to its normal operating
value.
• Fault Reset (Pin X). Momentarily connect Pin X to ground (Pin W) to reset
the high voltage fault and helix current fault.
Turning the High Voltage OFF will also clear these faults.
• AC Command Return (Pin Z). Common return.
Operation Without a Controller
To implement operation without a controller, the following jumper connections need to be made.
These connections can be made in the control connector mate: PT06E 18-32P.
1. Connect Pin a to Pin Z
2. Connect Pin F to Pin W
3. Connect Pin E to Pin Y
With these connections, the amplifier will be operational within 3 minutes of applying AC Power. If
the amplifier has a Latching Type Fault, it can be reset by momentarily turning off the AC Power.
Bias for the external control inputs need to be implemented with either the internal +15 VDC of the
amplifier or from an external DC supply. Both configurations are described in the following
paragraphs.
Using the Internal +15 VDC for Control (Connect E to Y): The control circuits for
systems that use the internal +15 VDC supply of the power amplifier are shown in Figure 2- 9.
Using an External DC Supply for Control into Pin Y: The control circuits for systems that use an
external +10 to +15 VDC supply are shown in Figure 2- 10.
These figures include the pinouts (a., b., c., etc.) of power amplifier connector J1. The equivalent “D”
connector pinouts for interconnect cable 350-0017-XXX, which is normally used to connect the
power amplifier to a TWTA controller are shown later in this chapter in Figure 2-14.
The operation of either configuration is the same. The control system connections are fail-safe.
Removal of the interconnect cable inhibits operation of the power amplifier.
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