Operation & Service Manual
Section II
Model 1805B RF Control Unit
Installation and Shipment
Figure 2-3 Model 1805B Connector Location (REAR)
IEEE-488 INTERFACE BUS (J3)
Joining the Model 1805B to a system controller requires the connection of IEEE-488 control
bus to the IEEE-488 INTERFACE BUS connector located on the rear panel (Figure 2-3). The
IEEE-488 INTERFACE BUS connector carriers program command and data signals passing
between the RF Control Unit and a system controller. Figure 2-4 shows the connector’s
contact pin numbering scheme and Table 2-1 lists the signal designator for signal present at
each contact pin.
Figure 2-4 IEEE-488 INTERFACE BUS Pin Location
- AM MODULATION Connector (J6)
Connector (J6) is a BNC-type connector which is located near the upper right-hand corner of
the rear panel. The signal present at J6 is a control voltage which provides RF level control to
signal generators, whose power output decreases with positive-going signal and increased with
negative-going signal. THIS OUTPUT WILL NOT FUNCTION CORRECTLY IF + AM OUTPUT
IS CONNECTED TO A LOAD.
Power Input Assembly (XF1)
The Power Input Assembly contains a three-prong ac power input connector and a voltage
selector/fuse assembly (Figure 2-3). The design of the Power Input Assembly prevents access
to the Voltage Selector PC Board or the Fuse Assembly while an ac power cord is connected to
the instrument. This design is not to be modified.
The AC Power Connector, located on the left side of XF1 (Figure 2-3), is a plug-type prong
insert connector with three conductors for connection of the power cord (P/N 068-21) to the
Power Supply Assembly located within the instrument. This connector also grounds the chassis
when the AC power cord is connected to a grounded wall outlet. If necessary, use a three prong
to two prong adapter and connect the adapter’s ground lead to the outlet plate retaining screw.
The voltage Selector/Fuse Assembly on the right side of XF1 reconfigures the RF Control Unit to
different operating voltages. This assembly contains a line voltage fuse and voltage selector
PC board. Refer to following paragraph for replacement of the fuse and/or proper alignment of
2-4
+AM MODULATION
Connector
-AM MODULATION
Connector
Power Input
Assembly
IEEE 488 BUS
Connector
