Measuring THD

[vincer]

I have externally looped the output of the 2810 to the input. The THD measures between .2 and .3 out to the third harmonic at 1 KHz using a Hamming Window. If the native THD of the instrument is over .1 % , How can I measure the THD of low THD amplifiers?

[VirtinsTech]

Thank you for your questions. Kaiser 6 window function is recommended for THD measurement. The loopback THD will be a little better if Kaiser 6 window is used instead of Hamming window.

More importantly, VT DSO-2810 is not designed to measure low THD as indicated by its own THD figures in the specifications.