Hi Bob, you can upload to http://www.imgur.com
Cheers, D. On Sun, Feb 23, 2014 at 8:07 AM, Bob Albert <[email protected]> wrote: > Pete, > > The EI is in three parts connected by many massive cables. When I say it's > pretty close, I mean it agrees with everything else I feel is close. The > 3456A has a -12V reference which the EI measures at -12.0026 or so. It uses > an oven so it takes a half hour to settle. I have pics of the panel and > would post them if I knew how. > > > The Valhalla is actually a good meter but one range has a small problem. The > Racal-Dana is unfixable because I can't find a manual, short of spending more > than the meter is worth. Those two units are very similar; the main > difference is 1) the Valhalla measures AC current and 2) the Dana has a very > sensitive DC microammeter such that I can measure diode leakage. > > I am befuddled by the HP3456A. I have replaced some parts but so far it's > not doing its thing. I have the manual but it sucks, not having a proper > schematic diagram nor a board trace layout. > > The Calib Stds unit is nice, a manually operated slideback DC volts only > unit, compact and easy to use. Again, no manual available and, in fact, no > mention of the company anywhere online. They were in Los Angeles area. > > The main reason I want to fix these is that I hate owning anything that > doesn't work. And I like knowing my meters are accurate as well as precise. > > I also have some 10V reference ICs that have been around here a few years. > They all agree within a few mV. I made a permanent reference out of them > with a switch to select each, and they are running whenever I am in the lab. > > Bob > > > > > On Saturday, February 22, 2014 6:31 PM, Pete Lancashire > <[email protected]> wrote: > > My take > > HP 3456A - Great meter. Manuals on the web. Has at least one HP custom > device that is a problem, other then salvaging from anohter 3456A is > unobtanium. The most complex of your collection. > > Valhalla 4440. Other then for the fun of fixing stuff not worth anything. > > Racal Dana 4200 Don't know it > > EI 3000. I don't have a 3000 but do have a lower cost variant. At least to > me a collectors item. You say "pretty close", pretty close to what ? I > believe it was EI that originated feedback in the Zener loop, finally > getting rid of the chopper. If anything the reference by now should have > settled down :-). > > Depending on your experience in repairing T&M, I'd use the Valhalla as a > way to get some. Then get a manual for the 4200 and repair it. Finally dive > into the 3456A. > > Love to see some inside pictures of the EI. > > -pete > > > > > On Sat, Feb 22, 2014 at 5:35 PM, Bob Albert <[email protected]> wrote: > >> I am the owner of a few fairly accurate and/or precise voltmeters and >> would like some information if it's available. >> >> >> First, my Electro Instruments model 3000 5-digit antique with Nixie tube >> readout, and the accessory AC converter. It hasn't been calibrated in >> decades but seems pretty close. I have no manual. >> >> >> Second is the recently acquired, not working HP 3456A. Struggling with >> that repair. >> >> Third is the Valhalla 4440. I have most of a manual but it differs >> somewhat from mine. Mine has an issue on one range of volts. >> >> Fourth is the Racal-Dana 4200. This works fine but after it warms up for >> a half hour starts to get erratic. >> >> Fifth is a Calibration Standards model DC-110A. No manual. It has some >> trouble on range overlap. >> >> Can anyone help me with any of these units? Documentation, reputation, >> etc. Photographs supplied if needed. >> >> Bob >> _______________________________________________ >> volt-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. > >> > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
