External Reference Signal Input Terminal (Ext Ref In, 10 Mhz 0 Dbm); Internal Reference Signal Output Connector (Int Ref Out); Unused Ports (Reserved); 11. Rear Usb Port - Agilent Technologies E4991A Operation Manual

Function Overview
Names and Functions of Rear Panel Blocks
If Option 1D5 High Stability Frequency Reference is installed in the E4991A, this terminal
outputs the reference signal.
NOTE
When Option 1D5 is installed, connect this terminal and "8. External reference signal input
terminal (Ext Ref In, 10 MHz 0 dBm)" to the option by using the included
BNC(m)-BNC(m) cable.

8. External reference signal input terminal (Ext Ref In, 10 MHz 0 dBm)

Connector type: BNC connector (male)
This is a signal input terminal used to phase-lock the E4991A test signal to an external
frequency reference signal. The accuracy of test signal frequency can be improved by
inputting the external frequency reference signal to this terminal.
When the external frequency reference signal is input to this input terminal, the E4991A
test signal is automatically phase-locked to its reference signal. When the signal input is no
longer generated, the frequency reference signal in the E4991A is automatically used
instead.
NOTE If option 1D5 has been installed, connect this terminal and "7. High stability frequency
reference output connector (Ref Oven, Option 1D5 only)" to the option by using the
included BNC(m)-BNC(m) cable.

9. Internal reference signal output connector (Int Ref Out)

Connector type: BNC connector (male)
This is an output terminal for the E4991A internal reference signal. By connecting this
terminal and the external reference signal input terminal of other equipment, it can be used
by phase-locking it with the E4991A reference signal.

10. Unused ports (Reserved)

These ports are not available. Do not connect any device here.

11. Rear USB port

This is a USB (Universal Serial Bus) port (number of ports: 2) used to connect a mouse, a
USB/GPIB interface, or a printer Using a mouse, you can efficiently make various settings
by freely moving the cursor across the E4991A LCD display. With the specified printer
connected to this port, you can print E4991A measurement graphs, measurement value
lists, settings lists, and other data. For the printers that can be used with the E4991A, see
ÅgPrinting Measurement Graphs and Internal Data ListsÅh on page xxx.
NOTE Be sure to only use a mouse, a USB/GPIB interface, or a printer designated for use with the
E4991A. Using a mouse other than those designated may cause incorrect actions to occur.

12. Mini-DIN mouse port (MOUSE)

This is a port used to connect a mouse equipped with a Mini-Din connector. Using a
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