Joe Having OCXO's, Rb's, Tbolt's and a Cs running with battery backup, over time I have used AGM, Ni-CAD, and now Ni-MH,, in all cases you have to have ventilation. Also battery and electronics have to be separated as much as possible since temperature is enemy #1 for any battery. Today most electronic charge circuits use pulse mode and the cell voltage goes as high as 1.8 Volt. In addition the battery has to be electronically separate from the user since having the Osc. connected directly to the battery will mess up the charge controller. I have a fast switch over that also cuts out the battery to prevent total discharge. If you are interested contact me directly. I recently ordered a Li-Ion 12 V 9.5 A pack, ebay # 140512699149, have not received it yet, but look forward testing it, to do the same with Ni-MH would cost three times as much and weight and size would be at least twice. Once tested I will share the results. I agree with the comment on using a Rb since there is no cost differential, just make sure that it has active or passive heat transfer to make sure that the batteries run as cool as possible. Bert Kehren Miami In a message dated 4/6/2011 3:14:06 A.M. Eastern Daylight Time, jg...@zianet.com writes:
If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG _______________________________________________ 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. _______________________________________________ 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.
