CHPA
S
ERIES
5-8
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For the Local, Remote, and Computer modes: On the front panel, press the LCL/RMT button to
toggle through all of the valid control modes (Local, Remote, CIF). If the CHPA is in the Remote
mode, the Serial Remote port may toggle control between the Remote panel (RMT) and the
Computer interface (CIF).
•
All control points will always provide status. Commands that modify either the CHPA’s
operating state or RF output will be accepted only from the valid control point.
•
The front panel button labeled LCL/RMT will toggle between all control points. The front
panel is the “super user” and may transfer the control point at any time.
•
If the control point is transferred to the Serial Remote port or the CIF, the Serial Remote port
may transfer control between itself and the CIF.
•
No control transfer may be commanded via the CIF port.
5.12 RF Control Modes
The CHPA features two RF Control modes:
•
ALC (Automatic Level Control) mode (ALC is displayed on Line 1)
•
Open Loop mode (nothing special is displayed)
Either mode may be selected under the RF Control category. Press the MENU button until Line
3 displays RF CONTROL; press the FUNCTION button until Line 3 displays RF MODE (see the
next subsection, “Special CHPA Functions,” for access to menu categories and Appendix B for a
detailed listing of all menu categories).
In
ALC mode
, the microprocessor controller adjusts the attenuator to maintain the RF output
power meter reading within ±0.1 dB of the RF output power setting (within the adjustment
limits of the attenuator and RF output limits of the CHPA). During Standby, the CHPA remains
in ALC mode, but the Attenuator Setting is frozen. If ALC is chosen while the unit is in
Standby, the attenuator will be set to maximum attenuation.
While in ALC mode, if the RF Output Power drops below 10 watts (W), the Attenuator Setting
is frozen until the RF Output Power exceeds 10 watts, or a new RF output power request is
made by the user. The CHPA will remain in ALC mode. This feature prevents the attenuator
from being adjusted to 0 dB if RF is removed from the unit.
If the user directly sets the attenuator during ALC mode, the CHPA will revert to Open Loop
RF Control mode.
In
Open Loop mode
, the microprocessor controller adjusts the attenuator to meet a requested
RF output power setting. Once that setting is attained (±0.1 dB), the Attenuator Setting is fixed
until the next Attenuator Setting or RF output power request is made by the user.
