Greetings, Have you found and checked out http://www.voltagestandard.com/ It is a neat and low cost package that I found quite helpful. Good Luck & 73 Gordon WA4FJC ======================================== Message: 1 Date: Wed, 23 Feb 2011 12:37:56 -0600 From: Charles <charlesmorris800@centurytel.net> Subject: [volt-nuts] Calibrating an HP 34702A? To: Volt-Nuts list <volt-nuts@febo.com> Message-ID: <dhkam65eev83r8epcp98n0ohukfon5jep7@4ax.com> Content-Type: text/plain; charset=us-ascii First post :) Having recently repaired a nonworking $5 hamfest special HP 34702A/34740A (4-1/2 digit DVM/display unit), I am interested in calibrating it. Without paying many times my purchase price to a lab! I obtained some sample MAX6325EPA (2.500V +/- 0.02%) which gets me "pretty close" for the 10V range. I also have a handy 596.5 ohm, 0.01% resistor for the Ohms ranges. The basic DC accuracy spec for the HP is something like +/- 0.03% plus 0.01% of range, so I need a better standard than that. Also I don't have a good way of generating very stable 10 KHz AC signals to cal those ranges... Much of the discussion on this list is 7.5 or 8.5 digit meters, so a 4.5 should be easy for you "Nuts". Any tips? thanks -Charles