Principal Test Conditions; Test Frequency - IET Labs, Inc. RLC Digibridge 1693 User And Service Manual

1693 RLC Digibridge
After measurement, the right-hand display will be
QDR, as usual; however, if the parameter selection
is C/R, the units for R will NOT be indicated. If the
parameter selection is C/R, t he ratio display in the
left-hand display area is accompanied by a resistance
value in the QDR display area, without unit s indica-
tion. If the ambiguity in units (ohms or kilohms ) must
be resolved, the following method is suggested . The
units can be determined for a typical DUT by tempo-
rarily disabling ratio display. While ratio is disabled,
make measurements also with parameter select ion
C/D and observe the typical value of D. Now you are
prepared to measure a batch of similar capacitors with
ratio display. For any of them , a temporary change
of parameter selection from C/R to C/D and another
measurement will provide a quick check on whether
its loss is similar to the loss of the typical DUT. If it is
similar, for similar value of C at the same frequency,
the R value is similar also. However if its D is much
higher, the value of Rs is higher and Rp is lower, in
approximate proportion to D.

3.4 Principal Test Conditions

3.4.1 Test Frequency

Power-up frequency is 1 kHz, unless the keyboard
has been locked with some other choice. There are
504 available frequencies, as detailed below. If a
frequency other than 1 kHz is selected, the "NOT
1 KHZ" indicator will light on the display window.
Selection. To select the test frequency, simply key in
the desired frequency as follows, and the Digibridge
will automatically obtain the nearest available one.
1. Select ENTER with the [FUNCTION] key.
2. Enter the desired frequency in kilohertz
and press [= ][SHIFT][FREQUENCY] in
sequence, as follows. For example, to select
[.][5][=][SHIFT][FREQUENCY]
500 Hz, press:
42
Up to 6 digits and decimal point are valid in entry of
desired frequency. For another example, if the desired
frequency is 2300 Hz, key in: [2][.][3][=] [SHIFT][FREQUENCY]
The actual frequency obtained appears immediately in
the left (RLC) display area. In the example of desired
frequency 2300 Hz, the display is 2.3077. The actual
frequency obtained is always the closest one of the
504 available frequencies, which can be calculated
from the following formulas , where n is always an
(3 kHz)(C/n) where n range is: 13 250 (freq .012000 to
integer in the range indicated:
0.23077 kHz)
(60 kHz)(C/n) where n range is: 4 256 (freq 0.23438 to
15.000 kHz)
(200 kHz)(C/n) where n range is: 1...13 (freq 15.385 to
200.00 kHz)
and where C = 1 + c, where c is a very small number
between - .000099 and + .000099
The "nominal value" of an available frequency can
be calculated from the appropriate one of the three
formulas, the appropriate value of integer n, and by
assuming that c = 0. The "corrected value" is more
accurate, and is calculated in the same way except for
using the true value of c.
The value of e is determined individually for each
Digibridge as part of its factory calibration. If you
want to find out what e is for your instrument, do
the following. (The value will be in the range : -99
to 99 ppm.)
Select ENTER with the (FUNCTION] key. Then
[SHIFT][SPECIAL][0]
press:
Indication. Frequency display is the nominal value,
to 5-digit resolution. This display is shown when
frequency is selected (as described above) or by in-
terrogation as follows: select ENTER function and
then press:
[SHIFT](FREQUENCY]
Operation