I don't understand the measurements regarding the voltage of the oscilloscope of the JDS6600 signal generator I recently bought.

Being the SGEN specified amplitude 5V I'd expect the Vpp on the oscilloscope to be 10v. Instead, I get 5.76V. Even if the amplitude in the SGEN actually refers to its Vpp, it still doesn't match the one reported by the oscilloscope.


  • \$\begingroup\$ at 10 kHz: Can you try with DC coupling, low-impedance input (50Ω) on the scope? Does it differ from AC coupling? from high-Z input? \$\endgroup\$ Aug 11 '19 at 10:55
  • \$\begingroup\$ AC coupling and DC coupling do not differ. I'd say I do not have 50 ohms input, but if i set the probe to x1 the peak to peak has fallen to 5.20, and the RMS to 1.76, which gives 4.97V assuming the amplitude of the SGEN is actually its Vpp. I'm pretty new to electronics.. why is that? \$\endgroup\$
    – perencia
    Aug 11 '19 at 11:20
  • \$\begingroup\$ because you're now loading the output of the signal generator. It's not a perfect voltage source, but comes with an internal resistance. In fact, for high-frequency applications, that is kind of wanted, because you'd need to match the impedance of the connectors and cables, which are 50Ω, typically. At 10 kHz, this plays no role whatsoever. \$\endgroup\$ Aug 11 '19 at 11:38

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