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Section
III
Paragraphs
3-35 to 3-38
Direct
Connection
Measurements
Model 4342A
3-35.
AQ
Measurement.
3-36.
When two Q values
are nearly
identi-
cal,
the difference
is difficult
to read
accurately
on the normal
Q scale.
The AQ
feature
of the 4342A provides
accurate
read-
ings
for
changes
in Q on all
Q ranges
by pro-
viding
ten
times
resolution,
namely:
0 to 3,
0 to 10, 0 to 30, and 0 to 100.
To make a AQ
measurement,
proceed
as follows:
a.
Connect
the sample inductor
to the
measurement
COIL (HI and LO) terminals
b,
Resonate
the inductor
using
the
same
procedure
as described
in Q Measure-
ment
(para.
3-34)
steps
b, c, d and e.
c.
Note panel
Q meter
reading.
d.
Depress
AQ button
and set AQ COARSE
and FINE controls
so that
meter
point-
er indicates
zero
(full
scale)
on AQ
scale.
e.
Check for
correct
resonance
by slight-
ly rotating
AC dial
control.
If
Q
meter
deflection
is not at peak,
re-
adjust
AC dial
and AQ controls.
f.
Make the desired
change
in the sample
or in the measuring
circuit.
g.
Adjust
L/C dial
control
for
maximum Q
meter
deflection.
Use AC dial
control
for
easily
taking
a precise
resonance.
If
meter
pointer
scales
out at the
left
end of the scale
(AQ full
scale),
reset
the function
to normal
Q
meas-
urement
and skip
steps
h and i.
h.
Read panel
Q meter
indication
on AQ
scale.
The AQ reading
is the differ-
ence in Q resulting
from the
change
made in step
f.
1.
The differential
Q value
(after
change)
is given
by the
following
equation:
Qz
=
Q1
-
AQ
. . . . . . . . . . . . . . . (eq.
3-3)
where,
Q1:
Q meter
reading
in step
c
(before
change).
Q2:
present
Q value
(after
change).
AQ:
Q meter
reading
from AQ
scale
in step h.
. 1.
When the change in Q exceeds AQ full
scale,
the difference
is given
by the
following
equation:
AQ
=
QI
-
Qz
. . . . . . . . . . . . . . . (eq.
3-4)
3-37.
Inductance
Measurement.
3-38.
The inductance
of a coil
can be
meas-
ured directly
from the Q meter
inductance
scale
at specific
"L"
frequencies.
The in-
ductance
range which
may
be measured
directly
at the "L"
scale
frequency
point
on the se-
lected
frequency
range
is labeled
on the
panel
adjacent
to the FREQUENCY RANGE push-
buttons.
To measure
inductance
at the "L"
frequency,
proceed
as follows:
a.
b.
C.
d.
e.
f.
g.
Connect
unknown to measurement
COIL
(HI and LO) terminals.
If
the approximate
value
of inductance
is known,
select
an appropriate
measuring
frequency
range.
Refer
to
the
chart
in Figure
3-4 or the induct-
ance multiplier
label
adjacent
to the
FREQUENCY RANGE pushbuttons.
For the
samples
whose values
are quite
unknown,
select
a trial
frequency
range.
De-
press
the
selected
frequency
range
pushbutton.
Set FREQUENCY dial
control
for
the "L"
scale
frequency
designated
by the mark
"-L-"
(shown in blue)
on the FREQUENCY
scale.
Set Q RANGE to 100.
Rotate
L/C dial
control
and verify
that
panel
Q meter
indicates
peak deflection.
If
a peak
meter
deflection
can not be recognized,
change to another
trial
FREQUENCY
RANGE setting
and repeat
the procedure
until
a peak is verified.
Set AC dial
to zero scale
(OpF).
Adjust
L/C dial
control
for
maximum Q
meter
deflection
(change
Q RANGE set-
ting
as necessary).
Read L/C dial
L scale
indicated
by the
fixed
scale
pointer.
To calculate
the
inductance
value,
multiply
the L scale
reading
by the factor
for
the selected
inductance
range.
Note
The measured
value
corresponds
to
the "indicated
L" including
meas-
uring
circuit
residual
factors
(similar
to "indicated
Q" value).
3-12
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