Radio Shack 22-174A - Measuring AC Voltage; AC Voltage Measurement and dBm Conversion; Measuring AC Voltage on a DC Bias; DC Blocking Capacitor Functionality

MEASURING
AC
VOLTAGE
WARNING:
DO NOT TRY
TO
MEASURE A VOLTAGE
GREATER
THAN 750
VOLTS
AC. YOU
MIGHT DAMAGE
THE
METER
AND
EXPOSE YOURSELF
TO
A
SEVERE SHOCK
HAZARD.
Follow
these
steps to measure
AC voltage.
Hint
When
you
use
the
meter
to
probe
for
a voltage in a high-volt-
age
circuit, do not try to
position
both
probes
at the same time. ln-
stead,
clamp the black lead
to
the neutral
or
ground
circuit lead
(usually
a bare,
green,
or white
lead)
using
an
insulated
SlipOn
Alligator
Clip
(Cat.
No. 270€54)
and
probe
for voltages with the
red
lead.
You
need to concentrate on
only
one test
probe,
so
place
vour
free hand in
your
baci<
pock6t
or
Blacl(
behind
your
back.
This helps
pre'
vent
you
from
accidentally touch-
ing
a hotwire
(usually
red,
black,
or blue) with the hand.
WARNING:
lF YOU CLAMP ON
TO
A HOT WIRE AND
TOUCH
A CONNECTED
TEST PROBES AT THE
SAME,
YOU
COULD RECEIVE AN ELECTRIC SHOCK.
MEASURING
AN
AC VOLTAGE
ON
A DC BIAS
This meter
contains a DG blocking capacitor,
which lets
AC
voltrage
pass
through it, but
blocks
DC voltages.
lf
the meter is
in
an AC voltage range,
the
DC
blocking capacitor
is enabled.
To measure
an
AC voltage
superimposed
on a DC voltage
source bias, follow the
steps
on Page
19
and
20.
Nsutral
or
Ground
Lead
Alllgator
Cllp
1.
Select AC volts
by rotati4g
the lunction
control
to
I.
v appears on the
display.
2. Plug
the black
test
lead
into
the meter's
-COM
terminal,
and
plug
the
red
lead into
the
meter's
+
terminal.
lo^
-@N,
*
4
J"@fl9^qPtr
F
lt
Black Red
3. Connecl the
probes
to the
voltage
you
will measure.
4. To change
the display to
dBm,
press
rtB.
The
display
shows the
reading
in dBm, and dBn
appears. To
change
the
reading
back to
volts,
press
dB again.
trc
.i &ro ur^
I
.Eruc?
J
le
,Nu'
5E-@
20
21