The Keithley Series 2000 is also THD capable!
"The 2000 THD series of Keithley Instruments are "Total Harmonic Distortion" analyzers, which are used for audio analysis and distortion measurements. The frequency range starts from 20Hz to 20kHz and a built-in low distortion sine wave Generator provide the adjustable signal for testing amplifier stages or speakers for distortion. Thus, for example in the production of mobile telephones, the microphone, the amplifier and the speaker part may be tested with this single device. The full digital multimeter part was taken from the model 2000 and allows measurements of 100 nV to 1000V."
No, they’re not saying the entire 2000 series is THD-capable. They’re saying the THD models
within the 2000 series are THD-capable.
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You're misunderstanding what the manual is saying. By "2000 THD series", they mean any 20xx THD meter, which is two. The 2015 THD and the 2016 THD.
Actually, it was four models: 2015, 2015-P, 2016, and 2016-P. The 2016 and 2016-P can output higher voltages on the test signal output, while the P versions can also “identify peak spectral components”. As best I can tell, the 2016 and 2016-P are discontinued. I’ve attached an old datasheet that covers them all. The current datasheet and website list only the 2015 and 2015-P.
(FYI, “THD” isn’t actually part of the model numbers, as there are no 2015/2016 models without THD functionality. The front panel text “2015 THD Multimeter” doesn’t mean it’s the “2015 THD” + “multimeter”, it means it’s the “2015” + “THD multimeter”. In fact, the -P models say e.g. “2015-P Audio Analyzing DMM”.)
The 2000 is just a DMM, and does not have the internal sine generator and THD measurement circuitry. The THD meters are a LOT heavier because they have a LOT more internally going on.
Yes, I am speaking from personal knowledge; I have a K2000 and a K2015THD, the THD meter weighs about half as much again as the plain DMM.
The OP doesn't mention a budget, and idk what the market is like in Greece, but I was patient and paid ~£400 for my K2015THD, with a fairly recent cal.
I paid about $400 for my 2015, too. It’s hands-down my favorite meter of all the ones I own (K2015, K197, K197A, Fluke 87V, Keysight U1252B, plus some cheapies).