Tuesday, July 16, 2013

Truevolt DMM Teardown, Review, and Additional Truevolt Topics

Today I'd like to highlight some videos that were published by the EEVblog. For those of you that don't know about Dave Jones and his blog, EEVblog.com has become one of the premier locations on the web for reviews and tear downs of Test and Measurement equipment.

The EEVblog forum is very active and many of the contributors are well informed and educated on different technologies. I have enjoyed reading the forum comments pertaining to the Truevolt DMMs.

Dave Jones has done a really great job and his review is overall very positive for Agilent's new DMMs. He's put a lot of work into both videos and provides a lot of insightful information for an independent review.

EEVblog #489 - Agilent 34461A Multimeter Review

EEVblog #485 - Agilent TrueVolt 34461A Multimeter Teardown

These videos and forums have brought up some topics that I think that I can address for the Truevolt DMMs.

How to get 1000 readings per second:

In order to get the fastest reading speeds you need to set the fastest integration time. For the 34461A, this is 0.02 NPLC. Also you need to turn off auto-zero and auto-ranging (by setting an explicit range). In the Acquire menu, you need to set the trigger delay to <90 micro seconds, a delay of 0 will get you better than 1000 readings per second.

With these settings you can get the maximum reading speed. The digit masking feature does not increase the reading rate, it only hides digits of resolution to provide easier reading for you. If there is enough interest I can provide a video to test this in the future. Let me know through a comment below or email me directly at david_tu@agilent.com.

Recalibration required after removing shield:

The printed circuit board actually has a label next to the shield that states "Recalibration required after removing shield".

There is some doubt from users that a recalibration is actually required. I spoke with the R&D engineers about this and their statement is below:
"Removing the shields affects AC flatness calibration. The adjustment calibration procedure compensates for small changes in capacitance from high impedance nodes to the shield. By removing and replacing the shields, these small capacitance values are changed and could affect the DMM's flatness calibration values." 

How can the 34461A be a replacement for the 34401A without RS-232?

Its true that the 34461A does not have an RS-232 port for I/O communication and this will deter many 34401A users from upgrading. I'm working on another blog post to address RS-232 users and I think that it will meet the needs for those of you that need RS-232 to control your DMM.