Controls, Connectors,
and
Indicators
DMM
All DMM controls are momentary push buttons. The buttons alternately select
and deselect functions. Refer
to
Figure 5-8 for the location of items 58 through 70.
@
@
®
RANGE
Buttons
AUTO
UP
and
DOWN
DC VI
DC
A
AC
V/AC
A
dBV/dBm
dBV
Select full-scale ranges for measurements.
Selects autorange. The measurement range changes
as necessary to maintain the reading within 9% to
100% of
full scale. Autoranging
is
automatically
selected
each time a new measurement function
is
selected. If auto ranging
is
active, pressing AUTO
deselects
autoranging. When the button
is
pressed
again, autoranging returns.
When a measurement range changes, the
display
blanks momentarily. If
a measurement exceeds a
manually selected range
or
the highest range with
autoranging,
"OVER"
is
displayed
in
the readout.
Change the measurement range.
In
autorange mode,
pressing either button
disables autoranging and
selects the next range above
or
below the present
range. Pressing the
UP
button at the highest range
or
DOWN at the lowest range does not change the
range, but changes the mode either from autoranging
to
manual ranging or from manual to automatic. With
manual ranging, the display shows "MNL."
With
manual ranging, measurements can exceed the
nominal full scale by 10%, except at the highest
range.
Turns the dc
volts or dc amps function on or off.
Selects
or
cancels ac rms volts
or
ac
rms amps.
Selects
or
cancels dBV or dBm.
Displays ac rms voltage measurements
as
the log of
the ratio of the input
voltage to 1
V.
Readings equal
20Xlog(VinputlVret)'
where
Vinput
is the input voltage
and V
ret
is
1
V.
With zero input, the readout displays
"OVER."
2465A/2455A/2445A Operators 5-27