Scans by ArtekMedia © 2007
mode voltages should not exceed
250
volts dc or peak ac when external
guarding is used).
CAUTION
Ifno external guard connection is used, leave the guard switch in the closed
("in") position to internally connect the guard shield. Do not operate the
HP 7090
without an internally or externally connected guard shield.
SIGNAL
INPUT
CLOSED ...
"IN" POSITION
HIGH
®
GUARD
LOW
INTERNAL
GUARDING
TO COMMON
MODE SOURCE
OPEN ...
"OUT" POSITION
HIGH
®
�
GUARD
LOW
•
<>--®
�
SIGNAL
INPUT
EXTERNAL
GUARD
CONNECTION
REOUIRED
Each input-signal jack accepts a dual banana plug. When applying input
signals, be certain to insert the positive terminal of the plug into the
HIGH
port of the jack. The
HP 7090
will accept peak or dc input voltages of up
to
200
volts. A schematic of the input terminal circuitry is provided In
Appendix
B
if you wish to determine impedance loading values.
WARNING
_
Insert the mains power cord before connecting channel input signals.
CAUTION
-=-
Applying input voltages in excess of
200
volts dear peak could damage the
HP 7090.
.-
For cases of extreme noise contamination of the ac power source, the
ground lug located on the right side panel of the
HP 7090
may be connected
to
the signal source chassis ground. In addition, sensitive measurements
may be adversely affected in the presence of strong magnetic fields. If this
occurs, reposition the
HP 7090
to
minimize field effect .
Guard·Switch
Positions
Channel Input
Signals
Measurement Setup Operations
3-23