Procedure

1. Setting the Frequency Generator for a High Z Load

The frequency generator defaults to a setting that is engineered to provide an accurate output readout when it is connected to a 50 ohm load. Digital oscilloscopes (like voltmeters) have very high input impedances. Thus, you must configure the frequency generator to output the correct terminal potential for a “High Z” load. Here's how:

Plug in an power on the frequency generator.
Access the Menu function by pressing the blue shift key, the press the Menu button just above it.
Press the > (side arrow) key until you see the Sys Menu (System Menu).
Press the down arrow key (just above the > key) until you see either “50 Ohm” or “High Z”. Press the side arrow key to toggle the setting.
Leave it set on High Z. Press the Enter Key (same as Menu).

This is something you will probably have to do every time you use Agilent 33120A frequency generator with an oscilloscope.

2. Set The Output Voltage

The frequency generator powers up with an output frequency setting of 1000 Hz and an output voltage setting of 100mV peak-to-peak (100mVPP). For this experiment, you should set the output voltage to 1.00VPP. Here's how:

Press the Ampl button.
Turning the adjustment knob will change whatever digit is blinking on the display. Make the left-most digit (probably "1") blink by pressing the < button (just under the adjustment knob).
Turn the adjustment knob until the output voltage is set to 1.000VPP.

3. Connect the Frequency Generator to the Oscilloscope

Power up the oscilloscope.
Connect a BNC cable from the output port of the frequency generator to channel 1 of the scope.
On the scope, find and press the Auto-Scale button, and observe that the plot’s vertical and horizontal scales are automatically formatted to display somewhat over one full cycle of the voltage fluctuation.
Now find and press the Quick Meas button, then depress the button below the scope screen that lies under the word Clear Meas. This will produce the default output. Your scope screen should look like this:

Verify that the scope readout agrees with the function generator readout. If your Peak-to-Peak voltage is off by a factor of two, go back to step 1.

Note: If your scope reports a VPP value that does not agree with your frequency generator setting, and you are certain that you have things set for a High Z Load, make sure the probe setting is set for no attenuation. To do this, press the lighted channel button above the signal input, and observe the Probe setting on the far right of the screen. It should be set for 1.0 : 1.

Other Quick Measurement Functions To Try

Measure the root-mean-square value of the voltage by pressing the arrow key to the right of the display screen row of buttons until you see RMS. Press the corresponding button. Verify that the RMS value reported by the scope is correct.

Press the Amplitude button and note that the value reported is the difference between the max and min value. This may not agree with your working definition of amplitude of a sine wave, but this is the way the scope is designed to work. Note the cursor lines that indicate the measurement region of the plot.

Press the arrow key until you see Period. Measure and confirm that it is correct. Note the cursor lines that indicate the measurement region of the plot.

Tinker With The Function Generator

More things to do: Configure the function generator to output square and triangle waves. Try noise. Have fun!

Benchmark the Function Generator and Scope

In this exercise, you will output waveforms over the operating range of the function generator.

Set the function generator for f_gen = 50 Hz. Measure and record VPP and the frequency f_scope using the scope.
Repeat step 1 for f_gen = 100, 500, 1000, 5000, 10kHz, 50kHz, 100kHz, 500kHz, 1MHz, 5MHz, 10MHz.
Make a plot of Log(f_gen) versus Log(f_scope) over the entire range of your data.
Let V_scope = VPP as reported by the oscilloscope, and let V_gen be the output voltage displayed on the frequency generator. Make a plot of V_scope /V_gen versus Log(fscope) over the entire range of your data. If you do not have agreement for every data point, which instrument is in error?