Operation & Service Manual
Section III
Model 1805B RF Control Unit
Theory & Operation
Power setting. If level control adjustments do not result in a lock, fault isolate the
problem using the system-level troubleshooting procedures given in the System IIA
Automatic Power Meter Calibration System Operation and Service Manual (IM-198).
Failure to renull (obtain lock) results in inaccurate calibrations.
g. For subsequent calibrations, repeat Steps b through f above.
h. When calibrations have all been completed terminate operation of the Model 1805B.
REMOTE OPERATION
The Model 1805B can be remotely controlled over an IEEE-488 bus by a standard bus
controller. Connect the controller to the IEEE-488 bus interface connector located on the rear
panel according to Section II. Set the Model 1805B's bus address using the rear panel
ADDRESS switch.
The Model 1805B recognizes commands sent via the IEEE-488 in the form of mnemonics
composed of a single ASCII character. Table 3-1 lists these mnemonics and provides an
explanation of each command. All commands must be terminated by ASCII codes for Line
Feed (OA) and/or an EOI with the last character. For more information on bus structure,
management, and terminology, refer to the IEEE Standard 488-1978, "Digital Interface for
Programming Instrumentation."
The REMOTE indicator is lit when the 1805B is placed into remote mode by the bus
controller. When the 1805B is addressed by the bus controller, the LISTEN indicator
illuminates and stays lit until another device on the bus is addressed. Set the desired DC
Substituted Power level using one of the mnemonics listed in Table 3-1. Monitor the 1805B's
BRIDGE BALANCE meter to ensure that the signal is locked. This is indicated by a
momentary deflection of the BRIDGE BALANCE meter followed quickly by a return to zero
(indicating a locked condition). If the meter deflection persists, rectify the condition. There is
no feedback to the bus controller that signals whether the 1805B is properly locked.
Table 3-1 Mnemonics for Remote Control
3-7
MNEMONIC
ACTION
0
Sets RF OFF
*
Sets RF ON and DC Substituted Power to .5 mW
1
Sets RF ON and DC Substituted Power to 1 mW
2
Sets RF ON and DC Substituted Power to 2 mW
3
Sets RF ON and DC Substituted Power to 3 mW
4
Sets RF ON and DC Substituted Power to 4 mW
5
Sets RF ON and DC Substituted Power to 5 mW
6
Sets RF ON and DC Substituted Power to 6 mW
7
Sets RF ON and DC Substituted Power to 7 mW
8
Sets RF ON and DC Substituted Power to 8 mW
9
Sets RF ON and DC Substituted Power to 9 mW
X
Sets RF ON and DC Substituted Power to 10 mW
