HP 400D, Инструкция по эксплуатации и обслуживанию

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Sect. Il Page 3
TABLE 2-1. EFFECT OF HARMONICS ON MODEL
400D/H/L
VOLTAGE MEASUREMENTS
Input Voltage Characteristics
Fundamental
=
100
Fundamental
+10% 2nd harmonic
Fundamental +20% 2nd harmonic
Fundamental +50% 2nd harmonic
Fundamental +10% 3rd harmonic
Fundamental +20% 3rd harmonic
Fundamental +50% 3rd harmonic
ith the instrument plugged into a power
source of specified voltage and frequency, and the
toggle switch at ON, allow the instrument about
five minutes t o reach a state of stable operation.
2)
Set the DB VOLTS (range) switch to the desired
voltage range.
3) Connect the voltage being measured to the
INPUT
binding posts.
4) The value of voltage being measured will be
indicated on one of two scales: O-to-l volt or
O-to-3 volts. When the range used contains the
integer "1", the value of the voltage being measured
will be indicated. on the I-volt scale: when the range
used contains the integer "3", the value of the volt­
age will be indicated on the 3-volt scale. Each
range switch position shows the maximum voltage
that can be measured on the appropriate meter scale.
,
CAUTION
When making power line voltage measurements with
this
instrument you must be careful to avoid a serious
short circuit. Connect only the red input terminal
to the side of the power line that produces approxi­
mately the correct indication on the meter and then
connect the black terminal to the other side of the
line. By following this procedure you will avoid
the short circuit that would result from connecting
the black input terminal which is grounded to the
ungrounded side of the power line.
b.
of decibels are made
in the same way as voltage measurements except
that the indication is read on the db scale (-12 t o
True
Value Indicated
RMS Value
by
Model
400D/H/L
100 100
100.5
100
102 100-102
112 100-110
100.5 96-104
102 94-108
112 90-116
+2 decibels). The level in decibels is the algebraic
sum of the meter db-scale indication and the DB
VOLTS (range) switch position.
1)
To read power directly in dbm (O rlbm
=
1
milli­
watt into
600
ohms), the measurement must be made
across 600 ohms.
2) Comparative db measurements (without respect
to the reference level) may be obtained by direct
reading provided each measurement is made across
the
same value
of
impedance. Madc
in this manner,
the difference in decibels between two or more
measurements may be obtained directly from the
db-scale indications.
3) To obtain the level in dbm with respect to im­
pedances other than 600 ohms, the meter correction
graph shown
in
Figure 2-1 may be used. The level
in dbm will be the algebraic sum of the level as in­
dicated on the meter and the correction shown on the
graph. For example,
U
the range switch is at the
+30 db pOSition, the measurement made across
90 ohms,
and
the indication
on
the DECIBELS scale
+1, the level in dbm is obtained as follows:
+ 1 (db scale indication)
+30 (range switch position)
'ill
(level in db as indicated by meter)
+
8
(correction for 90 ohms impedance)
+3'9"
dbm
For the same conditions, with the measurement
made across
60,000
ohms:
+
1
(db scale indication)
+30 (range switch position)
ill
(level
in
db as indicated by meter)
-20 (correction for 60,000 ohms impedance)
ill
dbm