HP 3468A - Page 26

RANGING (Cont’d)
Autorange
Autoranging
on
the
3468A
is
done
by
taking
readings
internally
in
the
4
1/2
digit
mode.
Measurements
are
made
on
successive
ranges
until
one
is
found
where
the
reading
is
between
full
scale
(301000
counts)
and
approximately
9%
of
full
scale
{027000 counts).
Ay Command
RA Selects autorange mode
Autorange Hysteresis
In
the
autorange
mode,
the
multimeter
will
up
range
(go
to
a
higher
range)
if
the
display
reading
exceeds
(+)
301000
counts
or
it
will
down
range
(go
to
the
next
lower
range)
if
the
display
reading
decreases
below
(+)
027000
counts.
This
assumes
a
5
1/2
digit
mode. These
numerical
autorange
points
are
irrespective
of
decimal
point
placement.
The
difference
between
the
two
points
is
called
the
autorange
hysteresis
and
is
illustrated
in
Figure
2-2
for
DC
Volts.
Autoranging
in
other
functions
is similar.
3oov} i { Laat
SON
i
je
P50!
RANGE
3v:
:
ow!
S00mV
beayep
i
i
30mv } : ; i |
ee
a
ne
ee
S&S = @ m 8 82
eo 6 =m 38s
= 8 2
5
INPUT LEVEL
=
DOWRANGE
POINT
>
2
UpRANGE
POINT
sa7en-2-2
Figure 2-2. Autorange Hysteresis
[2] [2]
The
3468A
is
put
in
the
manual
range
mode
in
one
of
three
ways:
pressing
the
AUTO/MAN
(Autorange/Manual
range)
key,
which
will
cause
the
meter
to
maintain
its
present
range;
the
UP-ARROW
key,
which
will
cause
the
meter
to
go
to
the
next
higher
range;
or
the
DOWN-ARROW
key
to
go
to
a
lower
range.
In
any
case,
when
the
3468A
is
in
the
manual
range
mode,
the
M
RNG
annunciator
is
on
in
the
display.
Pressing
the
AUTO/MAN
key
restores
autoranging.
HP
_]
|
Command
Manual Ranging
Be
4£S=
see Table 2-4.
20