Tektronix TDS 420A Oscilloscope Tips

Want more? Download the oscilloscope manual [PDF].

Recall Factory Setup

To recall the factory setup press the 'SETUP' button, then select 'Recall Factory Setup' from the lower context menu, and finally select 'OK Confirm Factory Init' from the right context menu.

How To Measure A Signal

When measuring values on the scope always expand the signal to fill as much of the scope screen as possible. Use the built-in measure features by pressing the 'MEASURE' button.

How To Measure Peak to Peak

These oscilloscopes have two built in ways of measuring peak to peak, 'Pk-Pk' and 'Amplitude'. 'Amplitude' removes overshoot from the measurement whereas 'Pk-Pk' does not. In this lab it is generally better to use 'Amplitude' to measure the peak to peak.

Paired Cursors

Turn on paired cursors by pressing the oscilloscope 'CURSORS' button and selecting 'paired cursors' from the right side context menu. Two vertical lines will appear on the screen. You can toggle between these two with the 'SELECT' button on the top left of the scope. The adjacent dial adjusts their horizontal position. On the top right of the screen the change in voltage and change in time between the cursors intersections with the selected channel will be displayed. It also shows the voltage at the intersection of the selected signal and cursor.

High Res Mode

Using 'Hi-Res' mode can smooth out noise in the data. To use Hi-Res mode, press 'SHIFT' then 'ACQUIRE MENU' and select 'Hi Res' from the right side context menu.

Average Mode

Average mode smoothes out noisy data by averaging the signal over multiple screen width intervals. This mode requires a stable non-rolling signal to function properly.

Activate Average mode:
Press 'SHIFT' then 'ACQUIRE MENU' and select 'Average' from the right side context menu.
Set the number of acquisitions to average:
Use the general purpose knob on the upper left to select the number of acquisitions (screen width intervals) to average.

Shut Roll Mode Off

To stop the waveform from rolling shut off roll mode. To do this press the 'HORIZONTAL MENU' button, then select 'Horiz Controls' from the lower context menu, and then toggle 'Roll Mode' until 'OFF' is displayed in the right side context menu.

Single Trigger Mode

Single trigger mode (aka single sweep mode) allows us to capture the transient behaviors of a signal.

Activate single trigger mode:
Press 'SHIFT' followed by 'SINGLE TRIG'.
Set the trigger level:
Turn the knob labeled 'MAIN LEVEL' to the same range as your trigger signal (default is channel 1). Be aware that noisy signals can produce extra trigger events.
Set the trigger position:
To start the data capture near the left edge of the screen (default is center), press the 'HORIZONTAL MENU' button. Then select 'Trigger Position' from the lower context menu and finally select 'Set to 10%' from the right context menu.
Set to stop after 'RUN/STOP' only:
To set the scope to capture data every time the trigger condition is met (default is single acquisition sequence), press 'SHIFT' then 'ACQUIRE MENU'. Then select 'Stop After' from the lower context menu and finally select 'RUN/STOP button only' from the right context menu.
Shut off roll mode:
It often helps to shut off roll mode.

AC Coupling Mode

'AC coupling' mode shows only the alternating components of an input signal. To use 'AC coupling' mode first select the channel that should be measured using 'AC coupling' mode. Then press the 'VERTICAL MENU' button, select 'Coupling' from the lower context menu, and finally select 'AC' from the right context menu. This only affects the selected channel.

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