HP 400E, Руководство по эксплуатации и обслуживанию

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Models 400Ej400EL Section V
AC VOLTME TER
TEST OSCILLATOR
hp
652A
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1
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Figure 5-3. Input Impedance Check
f. Repeat steps a through e in this paragraph
using a 50 ohm input, 1 volt thermal
converter and a + 1.000 volt dc output from
the dc standard. Set the 400EjEL to the 3
volt range and use the 50 ohm output of the
test oscillator.
5-23. 3mVand 1 mV Range Accuracy
Test.
a. Recalibrate the 10m V ref erence supply
according to the procedures in Paragraph
5-17 using a 0.45 volt thermal converter and
a 0 .3000 volt output f rom the dc standard.
b. Set S1 in Figure 5-2 to position B,
connecting the test oscillator output to the
thermal converter input. Connect the digital
voltmeter to the 400E/EL
DC
OUTPUT
terminals.
S E T T E S T O S C I LLATO R
OUTPUT TO MINUMUM BEFORE
C O N N E C T I N G . R E DU C E
OSCILLATOR OUTPUT BEFORE
C HA NG I N G F R EQU E NCY
RANG E . DO NO T ALLOW
OSCILLATOR O UTPUT TO
EXCEED RATED INPUT OF
THERMAL CONVERTER. ANY
O VERLOAD MAY DESTROY
THERMAL CONVERTER.
c. Set the 400E/EL RANGE switch to 3
millivolts ( .003 volts) and the oscillator to
10Hz. Connect a precision 40dB coaxial
attenuator between the BNC "T" connector
and the 400EjEL INPUT.
d. Using the oscillator amplitude control
as
coarse adjustment and resistor R4
as
a fine
adjustmen t, set the oscillator output so that
the thermal converter output nulls the
reference supply output.
e. Repeat step d for each frequency listed in
Table 5-2. If the 400E/EL is within
specifications, the meter indication and the
dc output will be within the tolerances listed
in the table.
f. Recalibrate the 10mV reference supply
according to the procedures in Paragraph
5- 17 using a 0.45 volt thermal converter and
a 0.3 162 volt output from the dc standard.
S E T T E S T O S C I LLAT OR
OUTPUT T O MINIMUM BEFORE
C O N N E C T I NG . R E DU C E
OSCILLATOR OUTPUT BEFORE
C H A NG I NG F R EQU E NCY
RANGE . DO NO T ALLOW
OSCILLATO R O UTPUT TO
EXCEED RATED INPUT OF
THERMAL CONVERTER. ANY
O VERLOAD MAY DESTROY
THERMAL CONVERTER.
g. Set the 400EjEL RANGE switch to .001
volts and set the test oscillator to 10Hz.
Connect a precision coaxial 50dB attenuator
between the BNC "T" and the 400E/EL
INPUT.
h. Using the oscillator amplitude control
as
coarse adjustment and resistor R4 (Figure
5-2) as fine adjustment, increase the
oscillator amplitude until the thermal
converter output nulls the reference supply.
Observe the 400E/EL meter indication and
dc output.
5-7