); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY On Tue, Sep 11, 2007 at 09:20:43PM -0600, Don Wisdom wrote: > Hi, > I was curious if anyone could tell me a little bit more about the DATUM 9390 > clocks. Primarly whether it uses a propatary antenna & whether it is > indeed gps based or loran or ?? Also if anyone has a manual available > that'd be cool.
I have one of the rubidium version I bought off Ebay several years ago. Somewhere (and I mean somewhere in tons of stuff) I have a partial set of prints and a manual, though I am not sure the prints exactly match the boards in my unit - there apparently were several revisions of the thing. My unit uses a very early Trimble GPS board that takes a normal 1574.2 MHz L band input (no special downconverter in the antenna or other non standard rf stuff). I have used it with conventional GPS antennas but as I remember by default it was wired for 12 volt rather than 5 volt power for the antenna. Changing this isn't too hard as it is quite possible to rewire the power feed for the antenna to 5 volts. I do remember the need to draw a certain amount of current from the antenna circuit in order to avoid a "antenna fault" message. Supposedly the Trimble board does carrier phase tracking, but how well this works on something so antique I do not know. Frequency reference for the receiver is derived from a VXCO that is phased locked to the disciplined Rb so the entire timing path is coherent. My original receiver card had the GPS date problem and took some fiddling to get the epoch right so it would compute the ephermides right and find satellites, eventually I obtained an upgraded receiver board with a PIC chip that twiddled the MSBs of the date message and does display the date correctly. At the moment my receiver is down as the 24 volt to +5 and +-12 volt DC to DC converter died and I haven't got around to finding a replacement that fits in the space provided. If someone on the list has a hanger queen with this board available I'd be interested.... -- Dave Emery N1PRE/AE, [EMAIL PROTECTED] DIE Consulting, Weston, Mass 02493 "An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either." _______________________________________________ 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.