IET Labs, Inc. RLC Digibridge 1693, User And Service Manual, Page: 51 / 171

27
1693 RLC Digibridge
Operation
3.2.11 Connection to 1482
Inductance Standard
Two methods that can be used when calibrating a 1482
Inductance standard is a direct method and a transfer
method, both are described below.
3.2.11.1 Transfer Methods
6-Terminal Transfer method : When lead inductance is
not sufficiently constant, its effect can be eliminated
by another method of comparison. The two six termi-
nal indictors can be connected in series to the bridge.
A first measurement is made with the short of one
inductor in the L position while that of the other is in
the Lo position on the reference terminals. A second
measurement is then made with both links moved to
the opposite terminals. The measured difference is
the difference between the two inductance changes
at the reference terminals and is independent of the
internal lead inductances because they appear in both
measurements and cancel in the difference.
The 1693 Digibridge is connected to the 1482-A
Inductance Standard as illustrated in Figure 3-20. A
14-guage piece of bus wire is used to connect between
the high terminals of both known and unknown stan-
dards. PH and IH are connected to the low side of the
known and
PL
and
IL
are connected to the low side
of the unknown. Shorting bars should short between
low and guard terminals for each standard.
3-terminal transfer method:
Two measurements are
performed with a 14 gauge bus wire moved so that
the inductance of the DUT is made and then the bus
wire is moved so that the measurement of the stan-
dard is made. The formula below can then be used
to determine the value of DUT.
Actual Value DUT = Known Value of Std
Measured Value of Std
*Measured Value of DUT
See Figure 3-22 for the 3-terminal transfer method.
Ratio measurements of 2:1, made on a 1689, on the
same range and using the delta% readout, typically
have errors totaling less than 20 ppm. This allows
comparisons of inductors of intermediate value (those
values starting with a 2 or 5) to be compared against
the even decade values with negligible added error.
3.2.11.2 Direct Measurement
Method
The 1482 Inductor can be directly measured on the
Digibridge. A combination of the 1689-9602 BNC to
BNC cable, two BNC T adapters and Pomona 1894
adaptors are used for connection. Open and Short
compensation should be performed. Spacing should
be maintained when performing open compensation.
To minimize noise the high leads are connected to the
low terminal of the 1482 and the low terminals to the
high terminal of the 1482.
Figure 3-20: Connecting 1693 to 6-terminal 1482
L
LOW
L
0
GND HIGH
formerly made by GenRad
100 µH
1482-B STANDARD INDUCTOR
L
LOW
L
0
GND HIGH
formerly made by GenRad
100 µH
1482-B STANDARD INDUCTOR
PL IL PH IH
14 gauge bus wire
1693 RLC DigiBridge
TM
.10000 948.8
POWER
uF
I
L
P
H
P
L
I
H
mH pF nF H k S DEG
NOT 1kHz
RANGE
HELD
CONST V.
PPM
START
NO
GO
GO
BIAS
ON
EXTERNAL
BIAS
REMOTE
CONTROL
On
Off
SER
On
Off
CONST I.
RATIO
mS uS
R C L Y Z G R D Q ANG B X
R/Q C/R C/D L/Q
PAR
Figure 3-21: Direct connection of 1693 and 1482
1693 RLC DigiBridge
TM
1.0000 484.1
POWER
uF
I
L
P
H
P
L
I
H
mH pF nF H k S DEG
NOT 1kHz
RANGE
HELD
CONST V.
PPM
START
NO
GO
GO
BIAS
ON
EXTERNAL
BIAS
REMOTE
CONTROL
On
Off
SER
On
Off
CONST I.
RATIO
mS uS
R C L Y Z G R D Q ANG B X
R/Q C/R C/D L/Q
PAR
LOW GND HIGH
formerly made by GenRad
1 mH
1482-E STANDARD INDUCTOR
PH IH
PL
IL