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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