Section V
Paragraphs
5-17
to
5-22
STD-A-0391
~
o t ,
M o d e l
403A
Connector, male
1251-0174
Connector,
m a l e ,
w/in-
|
1251-0175
sulator
L u g ,
t e r m i n a l
90°
0360-0042
R e s i s t o r,
100
K ohms,
0757-0839
=
1%,
1/2
W
Wa s h e r,
i n t .
lock
2190-0007
Spacer,
6-32
threaded
0380-0058
Shield
1251-0173
S c r e w,
b i n d . head,
6-32
| 2470-0001
x 1/4
i n .
b. Set Model403A FUNCTION to 15 C P S - 1 MC.
Set
RANGE to 1 V.
c. Set
test
oscillator
frequency
to100
cps.
Ad
‑
j u s t
amplitude
f o r a 1 V indication on
the
Model
403A.
d. Increase
test
oscillator frequency
u n t i lModel
403A
indication dropsto0.707V. This should
occur at a frequency of
637
ke or higher,
verifying an
input
capacity of less than 25 pf
on
the 1 V range.
e.
Resettest
oscillator
frequencyto100cps. Set
Model
403A
RANGE to
0 . 1
V.
Adjust test
oscillator
amplitude
f o r a
0 . 1 V
indication
on
the Model
403A.
f.
Increase
test
oscillator frequency u n t i lModel
403A
indication dropsto0.707V. T h i s should
occur at a frequency of
398 kc or higher,
verifying aninput capacity of 40pf or
less
on
the
0 . 1
V range.
5-17.
NOISE TEST.
5-18.
A shielded
100
kQ
load is r e q u i r e d
f o r
t h i s
test.
NOTE
Figure
5-8 l i s t s
the
parts and shows
the construction of
the 100
kQ
shielded
load.
a. Connect a shielded
100
kQ
load
across the
Model
403A
INPUT terminals as shown in
Figure
5-9.
Figure
5-9.
Noise Te s t
b. Set FUNCTION to 15 C P S - 1
MC;
set
RANGE
t o
0.001
V.
After
the
i n i t i a l
t r a n s i e n t ,
the
Model
403A should
indicate
between
0 and 6%
of
f u l l
scale.
This
verifies
noise lessthan
6% of f u l l
scale on the 0.001 V range.
c.
Switch
RANGE to
0.003
V.
M e t e r shouldin
‑
dicate between 0 and 3% of f u l l
scale.
d. Repeat step c f o r
the 0.01
to
300
V ranges.
On each
range the meter should indicate be
‑
tween
0 and 3%of
f u l l
s c a l e ,
verifying noise
of
less than 3% of f u l l scale on a l l ranges
above
0.001
V.
5-19.
A D J U S T M E N T
A N D
C A L I B R AT I O N .
5-20. The following paragraphs contain a complete
adjustment
and calibration procedure f o r the Model
403A.
Figures
5 - 1
and
5-2
show
the
location of the
internal
adjustments.
F o r
best accuracy,
the ad
‑
justments
should be performed in
the order
given.
5-21.
METER MECHANICAL
ZERO
ADJUSTMENT.
5-22.
The
meter
mechanical
zero should be checked
when
the instrument is at normal operating tempera
‑
t u r e ,
in i t s n o r m a l operating position, and
turned
00125-4
