Advertisement
battery
and
black
e
probe
tip
to
e
terminal
of the battery
to be
tested.
Read position
of the meter
scale.
If the reading
is
in
the
red
"BAD"
zone,
the
battery
should
be replaced.
If
the
green
"GOOD"
zone
the
battery
has considerable
life.
lf
reading
is white
"?"
zone
you
should
consider
making
a
replacement,
since very little
power is
left.
CAUTION:
Always
be sure that
you
identify
the
battery
polarity
correctly
before
testing
the battery.
DECEIBEL
RATIO MEASUREMENTS
The
ratio
of
two
AC voltages
can be expressed
in terms
of
dB.
A
standard
has been adopted
wh ich establ ishes one
refer-
ence voltage
as the 0 dB
level.
It is
0.774
volt
rms (root
mean
square).
This assumes
that
1
milliwatt
is.
developed
across an
impedance
of 600
ohms.
When using the
10 ACV
range,
read the dB scale if the V-n-A
slide switch
is set to V-A/2.
For dB measurements
on the other
NOTE:
Adjust
voltage
with
variac before
measuring capacitance
or
inductance.
Transformer
voltage
and shunt
resistor
require-
ments
are discussed
in the
text.
Do
not
change variac
voltage
after setting has been made.
.---
0
TRANSFORMER
l+r-
mil
10
VAC
120r12.5K
SEE
OR
OHMS
OR
TEXT
250
VAC
310K OHMS
110V
120V
VARIAC
SHUNT
AC
RESISTOR
FIGURE
2
-10-
AC
ranges
when
the
V·n-A
slide
switch
is in the V·A/2
position,
read the same dB scale
but
now
add
14
dB
when
set to the
50V range,
28
dB when
set to the 250V
range,
and
40 dB
when
set to
the 1000V
range.
When the V·n·A
slide switch
is
in the
V-n-A
position,
read the
same
dB scale on the meter
but
now
add
6 dB
in
the
10V
range,
20 dB in the 50V range, 34 dB
in
the 250V range, and 46 dB in the 1000V
range.
INDUCTANCE
MEASUREMENTS
1. Wire the
circuit
shown
in Fig. 2 using
a power
transformer
and
variable
AC
supply
voltage.
Connect
a
12-
or 12.5-K
ohm resistor
across
the test
leads.
(Note:
The 12- or
12.5-
K ohm
resistor
is used
across the
test
leads
when
measuring
inductance
and high capacitance.
A
31(}Kohms
resistor
is
used
across
the test
leads when
measuring
low capac
itance.)
Any
inductance
between
4
and
2000
Henrys
can
be
measured.
2.
Set the
RANGE
switch
to
10 ACV
and the
V-n·A
slide
switch
to
V-n-A.
Connect
the
test
leads across the secondary
of the
transformer,
as
shown
in Figure
2.
Starting
at zero
UNKNOWN
INDUCTANCE
~
OR CAPACITANCE
TRANSFORMER
~II
rl
LORC
120r12.5KOHMS
~
~
~1~KOHMS
120V
VARIAC
SHUNT
AC
FIGURE
3
RESISTOR
Circuit
to
measure
inductance
or
capacitance.
- 11-
Advertisement
