HP 11049A, Руководство по эксплуатации и обслуживанию, Страница: 11 / 19

Page 5
difference in outputs is called the dc reversal error.
The de reversal error is usually less than 0. 05% and
doesn1t affect most measurements, but it should be
compensated to achieve maximum accuracy. Instructions
for compensating dc reversal error are included in
the following calibration procedure.
20. CALIBRATION PROCEDURE.
21. The following steps describe a procedure for
generating 1 volt calibration signal that is flat within
the thermal converter specifications. Steps c through
f describe the procedure for compensating dc reversal
error.
If
the instrument under test is average or
peak responding, use a low distortion test
oscillator. A thermal converter and an
average responding circuit react diJferently
to distortion, and any distortion present will
create a calibration error between the
thermal converter and ihe instrument under
test.
a. Set test oscillator and dc standard outputs to
minimum.
b. Connect dc standard, test oscillator, thermal
converter, reference supply, null meter, and
instrument under test as shown in Figure 5.
Keep all connections as short as possible.
DC STANDARD
hp
7418
Model 11049A
NULLMETER
hp
419A
Figure 5. Test Signal Generation
c. Sei switch Sl in Figure 5 to DC, and set de
standard output to +1. 000 vdc.
d. Adjust reference supply for null indication
within less than 1 MV, Recordnull meter in­
dication (
)
.
Once null is obtained, do
not readjust reference supply output.
e. Reverse polarity of dc standard output and
record null meter reading (
)
.
f. Set 81 to AC and set oscillator frequency to 10 Hz.