Sencore FE149 - Page 7

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(eae on ie S a жы ed
150ЏА 500ША 1.5МА 5МА 15МА 5ОМА 150MA 500МА
and for the Ма ranges by 1, 10, and 100. For the 500 microamp, 5 Ма, 50 Ма, and
500 Ма ranges, the Ото .5 scale is used. Тһе readings are multiplied by 1000 for
the 500 microamp range and by 10, 100, and 1000 for the Ma ranges. If the meter
reads backwards when making current measurements, the leads are reversed. Тһе
meter polarity can be changed so that the meter reads in the proper direction by
simply depressing the opposite polarity DC CURRENT button on the Range switch.
To use the special 5 amp range of the FE149, insert the red test lead supplied into
the 5 A jack on the front panel. Depress the 500 Ma Range button and the plus or
inus DC CURRENT button. Use the red lead from the 5A jack and the ground lead
the FE149. Do not use the probe lead for the 5 amp current measurements as
it is not designed to carry 5 amperes of current. The 0 to .5 scale of the meter
will be used and the readings multiplied by 10 to give the current in amps.
Be sure to remove the red lead from the 5A jack when making other measurements
with the FE149. If the lead is left plugged into the 5Ajack, errorsin the other read-
ings taken with the FE149 will result.
MEASURING AC CURRENT: To measure AC current, the leads of the FE149 are
connected in series with the circuit where the current is to be measured and the
AC CURRENT button onthe Function switch and desired current range on the Range
switchare depressed. Тһе ЕЕ149 must be turned on whenmaking AC current mea-
surements. Тһе AC(V/MA) black scales are used. For the 150microamp, 1.5 Ма,
15 Ма, and150Ma ranges, the 0 (01.5 вса1е isused. For150 microamp range, the
reading is multiplied by 100 and for the Ma ranges by 1, 10, and 100. For the 500
microamp, 5 Ma, 50 Ma, and500 Ma ranges the 0 to .5 scale is used. For the 500
microamp range the readings are multiplied by 1000 and for the Ma ranges, by 10,
100, and 1000.
The special 5A jack on the front panel may be used to measure up to 5 amps of AC
current. Insert the red test lead supplied in the 5A jack and connect this and the
ground lead of the FE149 in series with the circuit. Do not use the probe lead of
the FE149 for 5 amp measurements. Depress the 500 Ma Range button and the AC
CURRENT button. Read the 0 to . 5 AC (V/MA) scale and multiply the readings by
10 to get the actual current in amps. When the ЕЕ149 is not being used to measure
5 amps of AC current, the test lead must be removed from the 5A jack. If left in,
errors on other readings taken with the FE149 will result.
MEASURING DECIBELS (db): Тһе FE149 has a convenient db scale for easy db
measurement. The eightranges are inperfect10 db steps for simplicity of measure-
ments. Тһе reference usedis 1 milliwattinto 600 ohms for 0 db. Dbmeasurements
are actually a ratio of AC voltages or power measurements from a given reference.
db decrease in a voltage would be actually .707 times the original voltage. A
b increase woule be 1. 41 timesthe original voltage. Because the db ratio cannot
always be taken across а 600ohms load, thechartin Figure 1 allows youto convert
the readings taken across differentresistive values and correlate them with the 600
ohm reference readings on the FE149 meter. For example, with readings taken
across a six ohm resistor +20 db should be added to the meter readings.
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