If the 681XXC contains an Option 16
high-stability time base, connect the coax-
ial cable between the 681XXC rear panel
10 MHz REF OUT connector and the 360B
rear panel 10 MHz REF IN connector.
Step 3 Connect one end of a GPIB cable, 1 meter
in length, to the 681XXC rear panel
IEEE-488 GPIB connector.Connect the
other end of the cable to the 360B rear
panel SOURCE CONTROLSYSTEM BUS
connector.
Step 4 Turnon the 681XXC and configure it as
described in the following paragraphs.
Modes of
Operation There are two 360B VNAreceiver modes of opera-
tion that are used with the 681XXC—the 360B
source lock mode and the 360B tracking mode. The
configuration and operation of the 681XXC for both
modes of operation are described in the following
paragraphs.
Source Lock
Mode When operating in source lock mode, the 360B
phase locks the frequency output of the 681XXC.
This is accomplished by sending a dc control voltage
to the FM input on the 681XXC. Due to the inherent
resolution of the 360B’ssynthesized local oscillators,
frequency resolution is limited to 100 kHz intervals.
Source Lock Mode Configuration
In order for the 681XXC to operate with a 360B in
source lock mode, the signal generator must be
placed in the SS Mode of operation.
Toplace the signal generator in SS Mode, first press
the main menu key SYSTEM . At the System Menu
display,press Config . The System Configuration
Menu (below) is displayed.
7-12 681XXC OMUSE WITH USE WITH A 360B VECTOR
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