Tektronix 1A1, Инструкция по эксплуатации

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Operating Instructions— Type 1A1
Fig. 2 -5 . Probe compensation waveforms using a 1-kHz calibrator signal.
observing a symmetrical 60-hertz square-wave signal. If a
10X attenuator probe is used with the Type 1A1, the low-
frequency response will be extended to about 0.2 Hz; with a
100X probe, low-frequency response is about 2 Hz.
Placing the INPUT SELECTOR switch to the GND position
grounds the input circuit of the Type 1A1 to provide a DC
zero reference. When the INPUT SELECTOR switch is set
to GND, the switch internally disconnects, but does not
ground the applied signal at the INPUT connector. The GND
position of the switch eliminates the need for externally
grounding the input of the unit or probe tip to establish
the ground reference.
VOLTS/CM Switch and VARIABLE VOLTS/CM
Control
The amount of vertical deflection produced by a signal
is determined by the signal amplitude, the attenuation fac­
tor (if any) of the probe, the setting of the VOLTS/CM
switch, and the setting of the VARIABLE VOLTS/CM control.
Calibrated deflection factors indicated by the settings of
the VOLTS/CM switch apply only when the VARIABLE VOLTS/
CM control is set to the CALIB position. Errors in display meas­
urements may result if the setting of this control is moved
away from the CALIB position; also, there may be a slight
change in transient response when a fast rise pulse is ob­
served.
The range of the VARIABLE VOLTS/CM control is at least
2.5 to 1 to provide continuously variable (uncalibrated) ver­
tical-deflection factors between the calibrated settings of
the VOLTS/CM switch. As the control is rotated a few de­
grees counterclockwise from the CALIB position, a switch
is actuated to increase the gain of the channel and pro­
vide overlapping coverage. When the control is turned to
its maximum counterclockwise position and the VOLTS/CM
switch is set to 20, the VARIABLE VOLTS/CM control ex­
tends the vertical-deflection factor to about 50 volts/cm.
By applying the oscilloscope calibrator voltage or any other
calibrated voltage source to the Type 1A1, any specific
deflection factor can be set within the range of the VARI­
ABLE VOLTS/CM control.
PULL FOR INVERT Switch
The PULL FOR INVERT (NORM-INVERT) switch may be
used to invert the displayed waveform, particularly when
using the dual-trace feature of the Type 1A1. The PULL FOR
INVERT switch has two positions. In the normal (in) posi­
tion, the displayed waveform will have the same polarity
as the applied signal; that is, a positive-going pulse applied
to the Type 1A1 will be displayed as a positive-going wave­
form on the CRT. If a positive voltage is DC coupled to the
Type 1A1, the beam will move up.
In the inverted (pulled) position, the displayed waveform
will be inverted; that is, a positive-going pulse applied to
the Type 1A1 will be inverted or displayed as a negative­
going waveform on the CRT. If a positive voltage is DC
coupled to the Type 1A1, the beam will move down.
MODE Switch
The MODE switch has five positions: CH 1, ALT, CHOP,
ADD and CH 2. These positions and their purposes are de­
scribed in the subsequent paragraphs.
Useful triggering
information is included in the description of the ALT and
CHOP switch positions.
CH 1, CH 2— Single-Trace Operation
To display a single signal (single-trace operation), apply
the signal either to the Channel 1 or Channel 2 INPUT con­
nector and set the MODE switch to the corresponding posi­
tion: CH 1 (Channel 1) or CH 2 (Channel 2).
To display a signal in one channel independently when
the same signal or a different signal is applied to the other
channel, simply select the signal in the channel to be dis­
played by setting the MODE switch to the appropriate
CH 1 or CH 2 position.
ALT, CHOP— Dual-Trace Operation
To display two signals together (dual-trace operation),
apply one signal to the Channel 1 INPUT connector and
apply the other signal to the Channel 2 INPUT connector.
Set the appropriate PULL FOR INVERT switch for normal
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