Signal Generator Problems/Solutions

1.  The oscilloscope is measuring twice what the signal generator voltage output is set to.
   
   Solution:
   Signal Generator Model 33220A: To Select the Output  Terminationa) Press  . b) Press the Output Setup softkey.
   c) Press the Load softkey to choose “High Z”.
   d) Select softkey DONE
   
   You must go through this procedure each time you turn on the HP 33220A.
   
   
   Signal Generator Model 33120A: To Select the Output  Termination
   
   a) Press Menu On. (Shift . Enter). You should see A: MOD MENU. on the display.
   b) Press the right arrow key three times. You should see D: SYS MENU on the display.
   c) Press the down arrow key once. You should see  1: OUT TERM on the display. This means output termination., which is your load resistance.
   d) Press the down arrow key again. You should see 50 OHM on the display.
   e) Press the right arrow key. You should see HIGH Z on the display.
   f) Press Enter. The instrument is now set for correct operation with high or varing impedance loads.
   You must go through this procedure each time you turn on the HP 33120A.  

2. Why does this occur? 
   The signal generator output termination is set to 50 ohm (power-up default) and in this case must be set to HIGH Z. Unfortunately for us, the engineers at Agilent who designed the signal generator assumed that most people would use it in RF applications which are generally 50-Ω loads. Thus, the default power up output termination is 50-Ω. If you wish to learn more read  Signal Generator Setup  or Principles of Signal Generators.
   
   Remember, every time you turn on the signal generator, you must set the output termination to HIGH-Z mode. If you fail to do this, you may accidentally produce voltages twice as high as you intend, and this may damage your chip.