9
4. OUTPUT VOLTAGE (AC):
Ranges:
0-2.5-10-50-250 (limited to 350 VDC)
5. DC MICROAMPERES:
Range:
0-50µA
Voltage Drop:
250 mV
6. DC MILLIAMPERES:
Ranges:
0-1-10-100-500 mA
Voltage Drop (Approx.):
250 mV, 255 mV, 300 mV, 500 mV
7. DC AMPERES:
Range:
0-10A
Voltage Drop (Approx.):
255 mV
NOTE: The 10A range is
not
internally fused.
8.
9. *ACCURACY:
77°F
67°-87°F
DC Voltage Ranges:
1.25% of F.S.
1.75% of F.S.
DC Current
0-50µA Range:
.75% F.S.
1.25% of F.S.
Other Ranges:
1.25% of F.S.
1.75% of F.S.
**AC Voltage Ranges:
2% of F.S.
3% of F.S.
Frequency Response:
Referenced to 100 Hz (Figures 4-2 and 4-4)
Resistance Ranges:
R x 1:
1.5% of Arc
1.75° of Arc
R x 100:
1° of Arc
1.25° of Arc
R x 10,000:
1° of Arc
1.25° of Arc
10. DECIBELS:
Ranges:
-20 to +10 dB, -8 +22dB, +6 to +36 dB, +20 to
+50 dB
Reference Level:
W/zero power level equal to 1 mW across
a 600
⍀
line.
11. BATTERIES:
1.5V, D Size, NEDA 13F 9V, NEDA 1604
12. FUSES:
F1: 1A, 250V, type 3AG, quick-acting Littlefuse
Type 312001, F2: 2A, 600V (Bussman Type
BBS or Littlefuse Type BLS)
13. TEST LEADS:
1 red, 1 black, 48” long.
14. SIZE:
5-1/2” x 7” x 3 1/8” (13.34 x 17.78 x 7.94 cm)
15. WEIGHT:
3 lbs. (1.359 kg)
16. ***RATED CIRCUIT-TO
-GROUND VOLTAGE:
1000V AC/DC Max.
*Accuracies specified are for the 270 in a horizontal position.
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24
Note:
The OHMS scale reads from right to left for increasing values of resistance.
e.
To determine the actual resistance value, multiply the reading by the factor at
the switch position. (K on the OHMS scale equals one thousand.)
4.19 Resistance Measurement of Semiconductors
Make sure that the OHMS range being used will not damage any of the semicon-
ductors (refer to Table 1-1, item 8, Section 1).
If there is a “forward” and “backward” resistance such as in diodes, the resistance
should be relatively low in one direction (for forward polarity) and higher in the
opposite direction.
Rotate the function switch between the two DC positions to reverse polarity. This
will determine if there is a difference between the resistance in the two directions.
To check a semiconductor in or out of a circuit (forward and reverse bias resis-
tance measurements) consider the following before making the measurement:
a.
The polarity of the internal ohmmeter battery voltage at the (+) positive jack is
identical to the function switch, polarity setting, and opposite to the (-) com-
mon jack.
Make sure that the OHMS range being used will not damage any of the
semiconductors (refer to Table 1-1, item 8, Section 1).
b.
If the semiconductor is a silicon diode or conventional silicon transistor, pre-
cautions are not normally required.
c.
If the semiconductor material is germanium, check the ratings of the device
and refer to Table 1-1, item 8.
NOTE:
The resistance of diodes will measure differently from one resistance
range to another on the same VOM with the function switch in a given position.
For example, a diode which measures 80 ohms on the R x 1 range may measure
300 ohms on the R x 100 range. The difference in values is a result of the diode
characteristics and is not indicative of any fault in the VOM.
Содержание 270 Series 5
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