I know what he was looking for, Jim. That's why I said 'wade through the 48V -> 12V models' - so he could get to the less common 12V -> 48V models that he wanted. I should have made that clear. :-) Telecom equipment is always spec'ed for ~54 volts. The battery strings consist of 24 (occasionally 25!) cells. To keep them healthy over their 20 - 25 year warranty period (!), they are occasionally given an equalize charge which can push the voltage up to ~56 volts. Of course, during an extended AC power failure, the voltage can drop well below 48V so the equipment has to function under those conditions as well. Ed Lux, Jim (337C) wrote: > > On 9/25/09 11:23 PM, "Ed Palmer" <ed_palmer@sasktel.net> wrote: > > >> Have you checked our favorite auction site? I saw some there by >> searching for '12v 48v converter'. Wade through the ones that are 48V >> -> 12V and there are a few that look interesting. One in particular >> from Vicor looked quite attractive. >> >> Ed >> > I think he was looking for 12V to 48V, which is substantially less common. > 48V to whatever is quite common, since 48V is a standard DC bus voltage. > > Of course, another problem is that the Z3801A doesn't use 48V. It takes more > voltage, from K8CU's site: The Z3801A is specified by HP (depending upon > model) as either a nominal minus 54 or plus 27 volt device. The best bet > is to keep the voltage at the nominal value specified by HP. This way any > out of specification internal DC to DC converters are satisfied, and the > units will perform normally. Reports from other users confirm this. > > > Mouser and Digikey both have a ton of DC/DC bricks with isolated inputs and > outputs. You can series the outputs (make sure you've got load resistors on > each one, and perhaps some diodes) > >

If you want cheap, use 6 12V to 9V DC-DC converters from old thin ethernet cards with the outputs in series! This will give 54V. You also get the isolation transformers and 10MHz filters see G4HUP's page http://g4hup.com/DA/10MHz%20Distribution%20Issues.pdf Robert G8RPI. --- On Sat, 26/9/09, Joseph Gray <jgray@zianet.com> wrote: > From: Joseph Gray <jgray@zianet.com> > Subject: [time-nuts] DC-DC converter > To: time-nuts@febo.com > Date: Saturday, 26 September, 2009, 2:59 AM > Does anyone know where I can get an > inexpensive 12VDC to 48VDC > converter to power one of my Z3801A's? I can find 12VDC to > 24VDC > units, like this one at Jameco: > http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=212514 > > Thanks. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >