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CHPA S
ERIES
3.4 RF Switch System Interface
The RF Switch System interface provides the relay-reported CHPA status and RF Inhibit
command required by a waveguide switch controller. Three relays provide CHPA status: Low
RF, Fault, and Sum Fault. The relay coil is de-energized to indicate a condition; this fail-safe
mode means that a loss of power will provide condition indications on all relays. The only
command on this interface, RF Inhibit, is active at all times and is not subject to the control
mode hierarchy. If an RF Switch port RF Inhibit is issued while the low RF Relay indicates a low
RF condition, the Low RF Relay will continue to indicate Low RF. Once the RF Switch Port RF
Inhibit disappears, the Low RF Relay will report existing conditions.
3.4.1
Relay Definitions
The Low RF Relay indicates that the CHPA's RF output is below the Low RF Alarm level or that
the CHPA is in the Fault state; a waveguide switch system usually uses this information to
trigger automated switching action. The Low RF Relay may be toggled to either Flexible mode
or Rigid mode via the front panel under the RF TRIP LIMITS menu selection. Press the MENU
button until the selection RF TRIP LIMITS is displayed. Press the FUNCTION button until the
selection LOW RF RELAY is displayed; use the arrow keys to select either FLEX (for Flexible
mode) or RIGID (for Rigid mode).
In Rigid mode, the Low RF Relay will indicate that the CHPA's RF output is below the Low RF
Alarm level any time this condition occurs, except during an RF Switch port RF Inhibit
command. The Rigid mode can be thought of as the strictest operation of the Low RF Relay.
In Flexible mode, the Low RF Relay will indicate the RF output is below the Low RF Alarm
level any time the condition occurs during the Transmit state, except during any RF Inhibit, and
during Fault state. Flexible mode allows switch controller operation in Automatic Switching
mode without triggering waveguide switch action while operating the CHPA in any normal
operating state or issuing RF Inhibit commands. Refer to table 3-2 for the two mode description.
The Fault relay indicates that the CHPA is in the Fault state—the CHPA features Auto Fault
Recycle capabilities and is capable under some circumstances of cycling back to a normal
operating state. This relay may be reassigned to indicate other conditions. Press the MENU
button until the selection RF TRIP LIMITS is displayed. Press the FUNCTION button until the
selection FAULT RELAY is displayed; use the arrow keys to select one the following:
•
FAULT—Fault state
•
LOW RF—Mimics the action of the Low RF Relay
•
SUMFLT—Mimics the action of the Sum Fault Relay
•
HV ON—Reports result of a logical equation: (High Voltage On) and (NOT(RF Inhibit))
•
XMIT—Reports High Voltage ON (See note 6)
The Sum Fault Relay indicates that the CHPA is latched into the Fault state. When the CHPA is
latched into the Fault state, the user must clear the fault source and issue a Reset command to
the CHPA to return it to a normal operating condition.
3-4
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