Calibration—P6047
BNC
adapter,
the
509
termination, and the
BNC-to-probe
adapter
to the output of the Type
109.
Connect the
P6047
Probe to the test
oscil-
loscope input connector and insert the probe
tip
into the probe
adapter.
See
Fig. 4-1.
b.
Set the test oscilloscope controls as
fol-
lows:
Triggering Mode
Normal
Slope
+
Coupling
AC
Source
Internal
Time/cm
0.1
yrs
Variable (Time/cm)
Calibrated
10X
Magnifier
Off
Volts/cm
20 mV
c.
Set the Type
109
Voltage Range switch to
5, Pulse
Polarity to
+,
and adjust test oscillo-
scope Triggering
Level
for a stable display.
Adiust Type
109
Amplitude for
4cm
of deflec-
tion.
d.
Using a non-conducting screwdriver, adiust
R4, R7, R9,
and
C5
for the best flat-top and
leading
edge
on the waveform. See
Fig. 4-2.
2. Ringing, Rounding,
and
Overshoot
Check
With the controls set as described
in
the
previous step, check ringing, rounding, and
overshoot for
£370,
in
addition to
that
of the
test oscilloscope.
3.
Risetime
Check
The P6047
is
designed to have a bandwidth
of
290
megahertz and a risetime of
1.2
nanosec-
onds. Since
this
response
is
considerably faster
than that of the test equipment commercially
available,
the probe risetime
must
be calculated
from
comparison of system bandwidth measure-
ments taken
with
and without the probe.
a. With the reactance meter, measure the
input
capacitance
of the oscilloscope or plug-in
unit
being used
(C1 in
the following formula).
b.
Assuming
that
the source impedance of
the constant amplitude signal
generator
used
to measure the bandwidth
is
259
(509
output
impedance terminated
in 50 Q),
calculate the
risetime of the input of the oscilloscope
by:
tr1
=
2.2
RC
=
2.2
X
25
X
C1
c.
Connect the constant amplitude signal gen-
erator, terminated
in 50 Q,
to the oscilloscope
input and measure the bandwidth
at
—3 dB
(BW1 in
the following formula).
d.
Calculate the risetime of the oscilloscope
when driven by a zero source impedance gen-
erator
by:
.35
2
V2
tr2
=
(3W1)
—tr12
e.
Connect the
P6047
Probe to the input of the
oscilloscope and measure, with the
reactance
meter, the input
capacitance
of the probe
(C2
in
the following formula).
f.
Calculate the risetime of the input of the
probe
by:
tr3
=
2.2
RC
=
2.2
X
25
X
C2
9.
Connect the
P6047
Probe to the output of
the constant amplitude signal
generator,
ter-
minated
in
50
S2,
and measure the bandwidth
at
—3 dB (3W2
in
the following formula).
INCORRECT
CORRECT
INCORRECT
Fig.
4-2.
High
Frequency Calibration.
4-2
