Tektronix 067-0587-01 - Page 23

CALIBRATION PROCEDURE 067-0587-01
the individual gain ranges, these voltages can be measured accurately.
These precision dividers are, however, entirely dependent upon the +50
volt and -50 volt power supplies generated by the oscilloscope mainframe.
Errors in these power supplies must, therefore, be taken into account be-
fore arriving at a final answer. The following formula is used to correct
the reading obtained in Step 9. For power supply errors:
Range X (E+ps + E-ps)
Corrected Reading = Reading- 200
Where: Range is the staircase step being checked (50 mV, 100 mV......)
Etps is the error of the + 50 volt power supply stated in per cent,
E-ps
is
the
error
of
the
-
50
volts
power
supply
stated
in
per
cent.
Example:
A
reading
of
+100.35
mV
is
obtained
on
the
100
mV
range.
A
+0.4%
error
is
noted
for
the
+50
volt
supply
and
a
-0.1%
error
is
noted for the -50 volt supply. The corrected reading would be:
100.35
my
-
200
av
o.4
—0-1)
.
100.35
mV
-
0.15
mV
=100.20
mV
Procedure
a. Plug the signal pickoff device into the Signal Standardizer.
Place
the
Signal
Pickoff/Signal
Standardizer
on
the
Flexible
Extender,
b.
Set
the
Signal
Standardizer
VERT
or
HORIZ
switch
to
GAIN.
c.
Measure
and
calculate
the
%
error
of
the
+50
volt
power
supply
and
~-50
volt
power
supply.
Record
these
errors
for
future
use.
A
conven-
ient
point
to
place
the
DVM
probe
for
measuring
the
+50
volt
power
supply
ig
ona
pin
4-19
of
the
plug-in
rear
connector.
The
-50
volt:supply
is
located at the pin B-19.
4-7