HP 3455A - Page 56

Model 3455A
Section
IV
a. Connect the
low
output of the DC Standard
to the
Low INPUT terminal
of the 3455A. Using short clip
leads, insert the I megohm
resistor in series
between
the
DC Standard’s high output
and the High INPUT ter-
minal of the 34S5A. Connect
a clip lead across the
resistor.
b. Set the 34SSA controls as
follows:
FUNCTION DCV
RANGE 10
V
HIGH RESOLUTION ON
GUARD ON
c. Adjust the DC Standard for a 3455A reading of
+
10.00000
V.
d.
Remove
the clip lead from across the I megohm
resistor.
e.
The 345SA reading should be between 9.99900 V
and 10.00000 V,
verifying
that the input resistance is
greater than
10'()
ohms.
f. Set the
3455A
RANGE to
100 V; Auto-Cal OFF.
Reconnect the clip lead across the I megohm resistor.
g.
Adjust the DC Standard for a
3455A
reading
of
+ 10.0000
V.
h.
Remove the
clip
lead from across the 1 megohm
resistor.
i. The 3455A reading should be
between
+ 9.0900
V
and +
9.0917 V, verifying
that the
input
resistance is 10
megohms ±
O.l'5'o.
4-56.
AC VOLTMETER INPUT IMPEDANCE TEST.
Equipment Required:
Test Oscillator (-hp- Model 6S2A)
Resistor (I MO
± 0.1
Vo
-hp- Part Number
0698-6369)
Resistor (100 kO
O.lVo
-hp- Part Number
0811-1997)
a. Set
the 34S5A controls as follows:
FUNCTION ACV
RANGE
1
V
GUARD
ON
INPUT
SELECT (rear panel) .... FRONT
AUTO-CAL
ON
b. Connect the Test
Oscillator 50-ohm output
(ter-
minated in SO-ohm load)
to the 34SSA front panel IN-
PUT.
c. Set the Test
Oscillator frequency to SO Hz and
ad-
just its output level
for a 34S5A reading of 1.00000 V.
d. Using short clip leads,
insert the 1 megohm
resistor
in series
between
the terminated Test
Oscillator
output and the
High INPUT terminal of the 3455A.
e. The 3455A reading
should be
between
0.66443 V
and
0.66887 V,
verifying that
the input resistance is 2
megohms
±
IVo.
f. Disconnect the resistor
and reconnect the Test
Oscillator output
to the 3455A INPUT.
g.
Set the Test Oscillator frequency
to 20 kHz and
adjust its output level
fora 34SSA reading of 1. 00000 V.
h. Using short clip
leads, insert the 100 kilohm
resistor in series between
the terminated Test Oscillator
output and the High
INPUT terminal of the 3455A.
i.
The
3455A reading should
be
greater
than
0.61017 V, verifying that
the input shunt capacitance is
less than
100
pF.
j.
Set the rear panel INPUT SELECT switch
to
REAR.
Connect the Test Oscillator 50-ohm
output (ter-
minated
in 50-ohm load) to the 3455A
rear-panel IN-
PUT.
k. Repeat Steps
c
through
i to test the input im-
pedance at the rear INPUT terminals. In
Step i, the
3455A reading should
be greater than 0.70822 V verify-
ing that the rear terminal
input shunt capacitance is less
than
75
pF.
4-19/4-20