Table of Contents
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Model 4342A
Section
III
Paragraphs
3-73 to 3-75
Series
Connection
Measurements
3-73.
SERIES
MEASUREMENTS.
C.
Note
Short-circuit
the unknown
(series
con-
nection
terminals)
with
a heavy
(low
impedance)
shorting
strap.
In the following
series
connection
measurement
procedures,
set 43424
Q RANGE as appropriate
unless
specifically
instructed
otherwise.
3-74.
Low Inductance
Measurement.
3-75.
Measurement
of small
inductors
at
relatively
low frequencies
can not be made
directly
at the measurement
COIL terminals.
However,
by using
an external
high
Q capaci-
tor
(such as the 16462A Auxiliary
Capacitor)
connected
in parallel
with
the
tuning
capa-
citor,
resonance
can be obtained
at the de-
sired
frequency.
A second method,
which
is
explained
here,
is the
series
method.
This
method
is recommended
for
measuring
low value
inductors
without
using
an external
capacitor
(but
with
an external
inductor).
When the measuring
circuit
is resonated
using
a reference
inductor,
the test
inductor
placed
in series
with
the reference
inductor
will
lower
the
tuning
frequency.
To restore
resonance
at the measurement
frequency,
the
tuning
capacitance
must be reduced.
The in-
ductance
of the unknown
inductor
can be
determined
from the relationship
between
the
tuning
capacitances
at the same frequency.
After
the sample
is connected,
quality
factor
and equivalent
series
resistance
can also
be
calculated
from a reduction
of panel
Q meter
indication.
Proceed
as follows:
a.
Depress
the appropriate
FREQUENCY
RANGE button
and set FREQUENCY dial
control
for
the desired
measurement
frequency.
b.
Select
a reference
inductor
which
allows
the measuring
circuit
to reso-
nate
with
a tuning
capacitance
of ap-
proximately
400pF.
Connect
unknown
inductor
in series
with
the reference
inductor
(between
measurement
LO
terminal
and low potential
end of the
reference
inductor)
and to measurement
COIL (HI and LO) terminals.
Note
If
16014A Series
Loss Test Adapter
is available,
attach
it
to measure-
ment COIL terminals.
Connect
the
reference
inductor
to appropriate
terminals
of the
16014A and unknown
inductor
to 16014A series
connection
terminals.
d.
Adjust
L/C dial
and AC dial
controls
for
a maximum Q meter
deflection.
Note sum of the C dial
and AC dial
readings
as Cl and panel
meter
read-
ing as Ql.
e.
Depress
AQ button
and adjust
AQ ZERO
(COARSE and FINE) controls
so that
meter
pointer
indicates
zero
(full
scale)
on AQ scale.
Note
Press AQ button
to release
AQ func-
tion
and recheck
for
correct
reso-
nance.
Again depress
the AQ button
and recheck
for
hQ zero indication.
f.
Disconnect
the shorting
strap.
Again
resonate
the measuring
circuit
by ad-
justing
L/C dial
and AC dial
controls.
Note sum of the C dial
and AC dial
readings
as C2 and panel
Q meter
AQ
reading.
If
meter
pointer
scales
out
at the
left
end of the
scale
(AQ full
scale),
reset
the
function
to normal
Q measurement.
The difference
in Q is
calculated
from
the two Q values
as
AQ
=
Q1
-
Q2.
Note
This procedure
(steps
c, d and f)
permits
the unknown component
to
be physically
connected
even
through
it
is electrically
out of
the
circuit,
and eliminates
pos-
sible
errors
by maintaining
the
relative
positions
of the refer-
ence inductor
and unknown
component.
g.
Inductance
of the unknown inductor
is:
l,s =
(zic;cf2)
(H) . . . . . (eq.
3-35)
Where,
W = 2~
times
the measurement
frequency.
Q value
of the unknown
is:
Q=
Q1Q2CC1
-
C2)
Cl (21
- C2Q2
".......
(eq.
3-36)
Where, 42 = Ql - AQ
Equivalent
series
resistance
is:
Rs = ($$I Q1 - 42 (n)
. . . . . (eq.
3-37)
~CI QI Qz
3-23
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