Approximately at July 2019 a member at Australian forum made the discovery of product design issue at Keithley DMM6500 model.
Keithley DMM6500 seems capable for V/I dual measurements’, this is a feature also found at Fluke 8846A but this has small limitations.
Fluke 8846A this can perform volt and current measurement when mode of operation this is set at DCI, then 2ND menu this activates volt meter (second smaller display top-right corner) at auto-range and the user has manual range control only at the DC current.
Now this Keithley DMM6500 while this appears more generous, dual display mode offer equal in size digits (for V/I) and even manual measuring range selection for both electrical parameters.
The new detected bug this is that when voltage range increased manually from 10V to 100V, the measured voltage this seems lesser by a few volts.
In other words it measuring accuracy this gets influenced beyond product measuring specifications’.
I do consider this as severe product flaw and of highest in importance bug ever detected at Keithley DMM6500 so far.
ITTSB Blog made the choice at 2019 to be disconnected from Keithley – Tektronix brand and products, due their unreasonable product support policy to not deliver even a plastic handle (DMM tilt bail) as spare part to consumer hands.
Primary goal of ITTSB Blog this is passing recommendations for quality products which also include spotless product support.
In that regard Fluke Corporation at 2019 this is no angel either but you may expect a more sincere and positive behavior if you get in troubles with one of their products.