SECTION 3
APPLICATIONS
Type 1A1
Introduction
This section of the manual describes procedures and tech
niques for making basic measurements with the Type 1A1
and the associated Tektronix oscilloscope. When only one
channel is involved, the step-by-step procedures use Chan
nel 1 as the example. If both channels are involved, as
when making phase-shift measurements, the reference sig
nal is applied to Channel 1.
NOTE
Although Channel 1 is used as the example in the
procedures in which only one channel is involved,
these same procedures can be used fo r Channel
2 by first applying the signal to Channel 2, then
setting the MODE switch to CH 2 and using the
appropriate Channel 2 fron t-pa ne l controls. A ll
the procedures assume that the Type 1A1 is used
with an oscilloscope which provides
6
cm o f usable
vertical scan. If the Type 1A1 is used w ith an
oscilloscope which provides a usable vertical scan
other than 6 cm, interpret the procedures accord
ingly.
No attempt has been made to describe specific applica
tions, since familiarity with the unit enables the operator
to apply these techniques to a wide variety of applications.
AC Component Voltage Measurements
Using One Channel.
To measure the AC component of
a waveform, the INPUT SELECTOR switch of the channel
you intend to use should be set to the AC position. In this
position, only the AC components of the input waveform
are displayed on the CRT. (However, when the AC com
ponent of the input waveform is very low in frequency,
use the DC position of the switch).
To make a peak-to-peak voltage measurement of the
AC component of a waveform, perform the following steps
(Channel 1 is used as the example):
1. Set the Channel 1 VOLTS/CM switch so that the volt
age to be applied to the INPUT connector is not more
than about six times the setting.
2. Apply the signal to the Channel 1 INPUT connector,
preferably through a coaxial cable or an attenuator probe.
3. Set the MODE switch to CH 1.
4. Set the triggering controls to obtain a stable dis
play and set the sweep rate to display several cycles of
the waveform.
5. Use the Channel 1 POSITION control to vertically
position the waveform to a point on the CRT where the
waveform amplitude can be easily determined. For exam
ple, position the waveform so that the negative peaks
coincide with one of the lower graticule lines and one of
the positive peaks lies near the graticule vertical center-
line (see Fig. 3-1).
6. Measure the vertical deflection in cm from peak to
peak on the waveform. Make sure the VARIABLE VOLTS/
CM control is set to the CALIB position.
NOTE
In measuring signal amplitudes, the width o f the
trace may be an appreciable part o f the overall
measurement. To make the measurement as accu
rate as possible, measure from one side o f the
trace (pa rticu larly when measuring low -am plitude
signals). Notice in Fig. 3-1 that points (A ) and
(B) correspond to the bottom side o f the trace.
The measurement would be just as accurate if
points (A ) and (B) corresponded to the top side
or center o f the trace.
7. Multiply the peak-to-peak distance measured in step
6 by the setting of the Channel 1 VOLTS/CM switch and
the attenuation factor, if any, of the probe.
As an example of this method, assume that the peak-to-
peak vertical deflection is 4.6 cm using a 10X probe with
the VOLTS/CM switch set to .5. Substituting these values
in the following formula:
Volts
_
Peak To Peak
Vertical
VOLTS/CM
Probe
deflection X
switch
X attenuation
in cm
setting
factor
Then:
Volts Peak to Peak = 4.6 X .5 X 10 = 23 volts
Using Channel 1 as a 10X preamplifier for Channel 2.
This procedure describes a method for making low-level
AC-component measurements with a 10X attenuator probe
without having to consider the probe attenuation factor.
The 10X attenuation of the probe is offset by the 10X
amplification of Channel 1. Thus, the following is the cor
rect formula:
3-1
