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試験装置 Allied Radio Knight KG-640のPDF 取扱説明書をオンラインで閲覧またはダウンロードできます。Allied Radio Knight KG-640 12 ページ。
ページを印刷するHOW
TO
MEASURE
RESISTANCE
CAUTION:
Before
making any resistance measurements
in a
circuit, make sure that the power is turned off. It is also good
practice to discharge any capacitors in the part of the circuit
in which resistance measurements are to be made.
[] Plug the black test lead into the jack marked
-COM.
Plug
the red test lead into the jack marked VOA.
AC
[] Place the polarity reverse switch in the +DC position. Place
the scale multiplier switch in the ao" position.
NOTE:
It will not be possible to zero the meter on any range
if the scale multiplier switch is set in the VA position.
[] Set the selector switch to the XI OHMS range. Connect the
two test lead ends together.
Turn
the OHMS
ADJ
control
until the meter reads 0 on the RED
scale marked a.
The XI ohms scale is now calibrated
to read ohm values from
0-1000 ohms.
Use this same
procedure to calibrate
the X100
and X10K
ranges before any measurements
are made on these
ranges.
Connect the test leads to the terminals of the unknown
resis-
tance to be measured. Observe the meter reading. Since great-
est accuracy is at the right hand side of the scale, switch the
selector switch to the range that provides maximum
deflection.
The
meter
should
be re-calibrated
frequently
for
accurate
readings.
With the selector switch set in the X1 position, the 0-1K ohm
range is covered; center scale reading is 12 ohms. Read the scale
directly.
With the selector switch set in the X100 position, the 100 to
100K ohm range is covered; center scale reading is 1200 ohms.
Multiply readings by 100.
With the selector switch set in the X10K position, the 10K to
10 meg ohm range
is covered;
center
scale reading
is 120K.
Multiply readings by 10,000.
When measuring resistance, a current is made to flow through
the unknown
resistance. Usually this current is so small that
it can be neglected. However, on the X1 ohms range, currents
as high as 180 milliamps will flow through
resistances
lower
than 6 ohms. Therefore it is good practice to consider the cur-
rent flow first when measuring the D-C resistance of a device
which can safely pass only low currents without being burned
out. For all other cases, no damage
will result as long as the
ohmmeter
current
does not exceed
the current
rating
of the
unknown resistance.