HP 400E, Operating And Service Manual

Page: 30 / 57

Section V
i. Repeat step h for each frequency listed in
Table 5-3. If the 400E/EL is within
specifications, the meter indication and the
dc output will be within the tolerances listed
in Table 5-3.
j. Place the 400E/EL RANGE switch to .003V
and repeat step h at 1/3 scale using the
frequencies listed in Table 5-2.
Refer to paragraph 546 for an
alternate calibration accuracy
check.
5·24. INPUT IMPEDANCE CHECK.
5-25. Input Resistance Check.
a. Connect the
SO
ohm output of the test
oscillator to the input of the 400E/EL.
b. Set the test oscillator and the 400E/EL to
the 3 volt range. Set the oscillator output to
40Hz, and adjust the output for a full scale
indication.
c. Connect a 100 kilohm resistor between the
test oscillator output and the 400E/EL input
as shown in Figure 5·3.
d. The 400E/EL indication should not drop
more than one small scale division from full
scale. This verifies an input resistance of 10
megohms.
5·26. Input Capaci ty Check.
5-8
a. Connect
a
test oscillator, a 100 kilohm
resistor, and the 400E/EL as shown in
Figure 5-3. Insert the resistor lead directly
into the BNC connector on the 400E/EL,
and connect the ground lead to the outer
shield of the 400E/EL input connector. Do
not use an adapter, as any adapter will add
input capacity.
b. With the 400E/EL on the 3 volt range,
adj ust the test oscillator for 3 volt reading
on the 400E/EL at 40Hz.
c. Increase the test oscillator frequency until
the 400E/EL indication drops to 2.12 volts.
This should occur at a frequency of 132kHz
or greater, verifying an input capacity of
1 2pF or less on the 3 volt range.
Models 400E/400EL
d. Repeat steps a and b with the 400E/EL on
the 1 volt range.
e. Increase the test oscillator frequency until
the 400E/EL indication drops to 0.707
volts. This should occur at a frequency of
63.5kHz or greater, verifying an input
capacity of 25pF or less on the 1 volt range.
5-27. AC TO DC CONV ERTER OUTPUT
IMPEDANCE CHECK.
5-28. Proceed as follows:
a. Connect an .hp- 651 B or 652A Test
Oscillator through a
SO
ohm load to the
input of the 400E/EL.
b. Connect a dc digital voltmeter to the dc
output of the 400E/EL located on the rear
panel. Set the 400E/EL to the 3 volt
RANGE.
c. Set the oscillator frequency to 100kHz and
the OUTPUT ATTENUATOR to 3 volts.
d. Adjust the oscillator amplitude to read
1.000 volts on the digital voltmeter at the dc
output.
e. Place a 1000 ohm
±
1 % metal film resistor
(-hp- part number 0757-0280) across the dc
output of the 400E/EL. The voltage should
read between 0.475 and 0.525 volts. This
varifies that the dc output impedance is
1000 ohms ±5%.
5·29. AC OUTP UT VOLTAGE CHECK.
5-30. Proceed as follows:
a. Connect a n oscillator (65 1 B or 652A) t o the
input of the 400E/EL through a
SO
ohm
load. Connect an ac digital voltmeter (-hp·
(3403C) to the ac output of the 400E/EL.
b. Place the 400E/EL and the oscillator on the
one volt range.
c. Ad just the oscillator's amplitude for full
scale deflection on t he 400E/EL meter. The
ac digital voltmeter should read 1
SO
m V
±
10% from 10 Hz to 4 MHz.
d. Decrease the range of the oscillator and
400E/EL to 100 mV and 10 mY, repeating
Step c for each voltage.