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depressed,
the
display
will
read
overrange,
signalling
the user to go to the next
higher
range. If 20M is depressed,
the display will read
zero
regardless
of the
voltage
applied.
The
method of calibrating
the converter
may yield an
offset up to 125 digits with the Model 177 input
shorted.
This does not affect
instrument
ac-
curacy.
2. Select the desired range from the five ranges available.
CAUTION
MAXIMUM
ALLOWABLE
INPUTVOLTAGE
(All
ranges):
IOOOV rme,
1400V
peak.
107V*Hz maximum.
Do not exceed the max-
imum
rating.
Instrument
damage may oc-
cur.
3. Connect
signal to be measured
between
INPUT HI and LO
terminals.
Observe
the displayed
digits and decimal
point
location.
The 200mV
range is direct-reading
in mV and the
remaining
four ACV ranges are direct-reading
in volts.
4. The crest factor (CFI is the ratio of the peak voltage to the
rms voltage
as follows:
CFrVPEAK
VRMS
NOTE
There will be some additional
measurement
error
for signals
with
a crest factor
greater than 3
fCF>3l.
Typical
crest factors are as follows:
Sine Wave
Square Wave
rriangular
Wave
Positive
pulse train
(duty cycle CF = 3 is 0.11)
CF = 1.4
CF = 1
CF = 1.7
CF = \/l/duty
cycle
5. The optional
Model 1682A RF Probe can be used with the
Model 177 to measure 0.25V to 15V rrn.s AC signals with a
frequency
of 2OkHz to 250MHz
(and above at reduced ac-
curacy).
6. Refer to paragraph
2.14 for TRMS
measurements
of a
signal with both AC and DC components.
2.11 RESISTANCE
KZ, MEASUREMENT
The Model 177 DMM measures resistance
from lmD/digit
to
20MD.
See Table 2-2 for ranges.
Nominal
settling
times to
within one digit of final reading are: three seconds on the 200
range; two seconds on the 2000kD and 20MD ranges; one se-
cond on the other four g ranges.
Use the Model
177 to
measure resistance
as follows:
1. Turn on power and depress the R pushbutton.
2-6
CAUTION
MAXIMUM
ALLOWABLE
INPUTVOLTAGE
(All
ranaesl:
350V oeak.
Do not exceed
maximum
rating.
l&trument
damage may
occur.
2. Connect
the circuit to be measured
to the INPUT binding
posts
and
select
the
desired
range
from
the
seven
available.
?iii%gzm
x;
il binding
post treol IS negatrve.
Range
Maximum
Setting
Reading
200*
19.999
2ooll*
199.99
2kD
1.9999
20kD
19.999
200kD
I
199.99
2000kR
1999.9
20MD
19.999
*Front
Panel
Zero
Table 2-2. Resistance
Ranges
Full Scale
Voltage**
20mV
200mV
2v
2v
2v
2v
2v
All Ranges
Nominal
Applied
Current
1mA
1mA
1mA
1OOfiA
1 Oj.cA
ld
O.lfiA
3. Observe the displayed
digits and decimal point to measure
resistance
using
the 2k, 20k. 200k.
2000k
and 20MR
ranges. The full scale voltage
drop for these ranges is 2V
which
is sufficient
to
cause
forward
conduction
of
semiconductor
junctions.
The
HI
(Red)
terminal
is
negative.
To
measure
a resistance
in parallel
with
a
semiconductor
junction
without
turning
on the junction,
either reverse bias the junction
or select the next higher D
range. The latter method
is possible
because
of the one
decade reduction
of applied test current,
but will result in a
measurement
with 3% digit accuracy.
It is suggested
that
the 2kg range be used for diode testing.
This range has a
nominal
1mA test current and the displayed
reading is the
forward
voltage
drop in volts.
NOTE
The front panel ZERO control
operates
only on
the 200 end 2OOD ranges. It has no effect on the
other resistance
ranges.
4. Before making measurements
on the 2051 or 200R ranges,
adjust front panel ZERO on the 20R range to compensate
for test lead resistance.
Best performance
will be obtained
on the low ohm ranges when test connections
are made to
the binding
posts, rather than using banana plugs. Adjust
ZERO and make resistance
measurements
as follows:
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