Keithley 178 User manual

INSTRUCTION MANUAL
Digital Multimeter
Model 178
SPECIFICATIONS
DC VOLTAGE
RANGE MAXIMUM READING
ACCURACY (12 months)
18°-28°C
±(% rdg + digits) MAXIMUM
ALLOWABLE INPUT
1.9999
2OV 19.999
200 v
199.99
1200v 1200.0
Temperature Coefficient
(0°-18° and 28°-55°C):
+(0.006% + 0.2 digit)/°C
Input Resistance: 10 M Q ±0. 1%
Settling Time: 1 second to within 1 digit of
final reading.
0.04% + 1d 1200V momentary
0.04% +1Id 1200v
0.04% +1Id 1200v
0.04% +1Id 1200v
Normal Mode Rejection Ratio:
Greater than 60dB at 50Hz and 60Hz.
Common Mode Rejection Ratio (lkfi unbalance):
Greater than 120dB at DC, 50Hz and 60Hz.
AC VOLTAGE
RANGE
2v
20 v
200 v
1000 v
MAXIMUM
READING
1.9999
19.999
199.99
1000.0
ACCURACY (12 months) TEMPERATURE COEFFICIENT
(above 2000 counts)
0°-I 8° and 28°-55°C
18°-28°C; 1 00Hz-1 Ok Hz
±(% rdg + digits)/°C
±(% rdg + digits) 45Hz-10kHz I0kHz-20kHz
0.4% + 15d 0.04% +
0.5d
0.09% + 0.5d
0.3% + 15d 0.01% + 0.5d 0.03% + 0.5d
0.3% + 15d 0.01% +
0.5d 0.03% + 0.5d
0.3% + 15d 0.01% +
0.5d 0.03% + 0.5d
Extended Frequency Accuracy: Input Impedance:
(45Hz-100Hz) ±(0.5% + 15 digits)
IMfi + 1% shunted by less than 75pF.
(10kHz-20kHz) ±(1.0% + 15 digits)
Maximum Allowable Input Voltage:
Response: Average responding calibrated in rms
1000V rms, 1400V peak, 10
7
V·Hz maximum.
of a sinewave. Common Mode Rejection Ratio (lkfi unbalance):
Settling Time: 2.5 seconds to within 10 digits 60dB at DC, 50Hz and 60Hz.
of final reading.
RESISTANCE
ACCURACY (12 months) TEMPERATURE COEFFICIENT
MAXIMUM
18°-28°C
0°-1 8° and 28°-55°C
NOMINAL
RANGE READING
±(% rdg + digits) ±(% rdg + digits)/°C APPLIED CURRENT
2kQ 1.9999
0.04% + 2d 0.003% +
0.2d
1mA
20 kQ 19.999 0.04% + Id0.003% + 0.2d
200 kQ
100~ A
199.99 0.04%+Id0.003% + 0.2d 10~ A
2000 kQ 1999.9 0.04%+Id0.003% + 0.2d
1P A
20Ma 19.999 0.10%+ 1 d 0.02 % + 0.2d 0.1~ A
Maximum Allowable Input: 250V rms sine, 350Vpeak.
Maximum Voltage Across Unknown: 2V within range,
5V open circuit.
GENERAL
DISPLAY: Five 0.5” LED digits, appropriate
decimal position and polarity indication.
CONVERSION PERIOD: 400 milliseconds.
ENVIRONMENT:
Operating:
0°C to 55°C;
0% to 80% relative humidity up to 40°C.
Storage: -25°C to +65°C.
Settling Time: 1 second to within 1 digit of final
reading except 2 seconds on the
20Mfi range.
POWER: 105-125 or 210-250 volts (switch selec-
ted), 90-I
10V available. 50-60Hz, 7 watts.
Optional 6 hour battery pack, Model 1788.
DIMENSIONS, WEIGHT: 85mm high x 235mm
wide x 275mm deep
(3-1/2 in. x 9-1/4 in. x
10-3/4 in.). Net weight: 1.7kg (3lbs., 13 oz).
OVERRANGE INDICATION: Display blinks all
zeros above 19999 counts.
MAXIMUM COMMON MODE VOLTAGE: 1400V peak.
AA

INSTRUCTION MANUAL
OPERATING INSTRUCTIONS
Digital Multimeter
Model 178
2-77
.
OPERATING INSTRUCTIONS. Refer to Figure 2-3 and operate the DMM as follows:
a.
Turn on the power by depressing the ON/OFF pushbutton.
b
l
Select the function with the DCV, ACV or 52 pushbutton.
c.
Select the range by depressing the appropriate pushbutton. For ac and dc voltage
measurements there are four ranges available. For resistance measurements there are
five ranges. The pushbuttons are interlocked to avoid improper settings.
d
. Connect the source to the INPUT terminals.
POLARlTY (NEGATIVE IS INDICATED, POSITIVE IS IMPLIED WHEN MINUS (-) DISPLAY IS OFF)
DCV ACV
ELECT FUNCTION SELECT RANGE CONNECT-SOURCE
*ADJUST ZERO AS REQUIRED FOR MEASUREMENT OF DC VOLTAGE AND RESISTANCE. SEE SEC. 2-11.
FIGURE
2-3. Operating Controls.
CAUTION
MAXIMUM RATINGS:
n
DCV:
(2V): 45OV rms continuous; 12OOV peak, for 8 seconds per minute.
(20-1200V): 12OOV peak.
ACV: (All Ranges): 1OOOV rms; 10
7
V·Hz.
a:
(All Ranges): 25OV rms sine wave or 35OV peak.

2-8 .
DC VOLTAGE MEASUREMENT. Use the Model
178 DMM to measure dc volts as follows:
a.
Turn on power and depress the DCV pushbutton.
b.
Select the desired range from the four ranqes available. The maximum reading is
19999.
Over range is indicated by a flashing 0000 except on the
1OOO-volt range.
CAUTION
n
1 Do not exceed the maximum ratings.
.
Instrument damage may occur.
C.
Neqative polarity is displayed automatically. Positive polarity is implied
when
the minus
(-) display is off.
d
Zero the instrument as described in Paragraph 2-11 before the first use, whenever
the’instrument is used outside the temperature range of 18" to 28°C, and approximately
weekly
,during normal
use.
2-9
. AC VOLTAGE MEASUREMENT. Use the Model 178 DMM to measure ac volts as follows:
a.
Turn on power and depress the ACV pushbutton.
A
I
.
CAUTION
Do not exceed the maximum ratings. Instrument damage may occur.
b
19999
Select the desired range from the four ranges available. The maximum reading is
Overrange is indicated by a flashing 0000 except on the
lOOO-volt range. The
instrument reads the root mean square value of a sine wave with a frequency of 45 to 20
kHz.
c.
The Model 1682 RF Probe (see Paragraph 2-12e) should be used to measure ac voltages
with a frequency of 20kHz to 100MHz.
. .
2-10. RESISTANCE (R) MEASUREMENT. Use the 178 DMM to measure resistance as follows:
Turn on power and depressthe
Sz pushbutton.
CAUTION
n
1 Do not exceed the maximum ratings.
.
instrument damage may occur.
b
19999
Select the desired range- from the five ranges available. The maximum reading is
Overrange is
M refers to meqohms. indicated by a flashing 0000. The letter k refers to
kilohms, and
c.
The HI inputterminal is positive and causes forward conduction of semiconductor
junctions.
d
.
Two volts is applied at full range with 5 volts maximum under open circuit conditions.
Zero the instrument
as described in Paragraph 2-11 before the first use whenever
theainstrument is used outside the temperature range of 18° to 28°C, and approximately
weekly during normal use.
2-11.
ZERO ADJUSTMENT. The zero adjustment nulls input offset on the 20, 200 and 1200
volt ranges and on all resistance ranges. Typically, this adjustment need
not be per-
formed more often than once a week unless the instrument is operated at ambient
temperatures outside the range of
18° to 28°C.
Zero adjustment may also be used for lead
compensation on the
Q function.Zero the instrument as follows:
a. Turn on the power and select DCV and the 20 range.
b. Plug in test leads and short them.Adjust the zero adjust (pot
R132) from the
front panel with a small screwdriver to obtain a reading of 0000 or -0000.
2-12. ACCESSORIES. A
wide range of accessoriesis available to facilitate use of the
Model
178 DMM, extend its range and adapt it for additional uses.