Hi Bill, I thought about using a Fluke 750A instead of the 752A or the 720A. However, upon examining the specifications of the 750A, I discovered that it has a lot higher uncertainty than the 720A and the 752A. The 750A is specified at 10ppm uncertainty, whereas the uncertainty of the other two dividers is well below 1ppm. Charlie Message: 4 Date: Sun, 19 Sep 2010 23:54:32 -0700 From: WB6BNQ <wb6bnq@cox.net> Subject: Re: [volt-nuts] Fluke 720A Kelvin Varley Divider Questions To: Discussion of precise voltage measurement <volt-nuts@febo.com> Message-ID: <4C970527.4BF31169@cox.net> Content-Type: text/plain; charset=iso-8859-1 Hi Charlie, First off you are using the right email address to send to the list. The "reply to" function of your email program should automatically put that same address in when replying to. My experience with the 720 is that it holds quite well, assuming that it is not abused. Besides, you can easily re-cal it at any time. There is no reason why you could not use the 720 for calibrating the 5440B as far as I can see. As for the 752, you could use the 750 instead and those are around and would, or should, be cheaper. They perform the same function as the 752, just a slightly older model with yet more capability than the 752. Bill....WB6BNQ