I picked up yet another version of a GPSDO on Ebay the other day. I thought that I'd mention this because sometimes when one unit shows up there are a lot more that will be listed for sale later, like with the many Lucent RFTG units that are currently being sold on Ebay.
This one is a Symmetricom CGBA with absolutely no info other than the photos in the listing. The board is about 9"x13" and has date codes from 2003. It has a Symmetricom 5Mhz OCXO that feeds a doubler with L/C filtering and a 10Mhz crystal to further filter the 10Mhz and give a nice clean sine wave feeding a 27 ohm termination resistor. Then the signal goes to 3 EL2257 dual gated opamps That seem to make the signal look much worse so there may have been more than one design engineer on this project. ;-) I traced out 2 lines for power, each one goes thru its own fuse to a diode bridge so it doesn't care about polarity. >From the bridge the power goes to several discreet onboard switchers that give +12, +12 OCXO, -12, +5, and +3.3VDC. I found that the minimum voltage to make the board operate was 22-28VDC so I'm running it on 36VDC. The current draw is 0.5A cold to 0.25A with the OXCO warmed up. The GPS is made by Furumo and has what looks like an HP part number 0960-1060(HP31) and has +5VDC for an active antenna on the antenna connector. There are unused pads on the main board for SMA size connectors that are marked 10M, PP2S, 4.096M, 100Hz, 30.72M, 40.96S, and 8K. Not all of these are active and the 3 dual opamps are not 'on' either so some of the pins in the connectors on the back of the assembly may do some controlling of signals or these may be options not implemented on this board. When powered up it goes through a light flashing sequence then the GPS LED goes flashing green when it sees the satellites, then solid green when it locks, and the ACT LED turns from flashing red to flashing green. Using my modified Tbolt to test the unit shows it stays within +/-200PPT for about the first 2 hours then settles down. There is an RJ-45 connector on the front plus there is a 15 pin 'D' connector behind the panel that may have been for some testing purpose because it can't be accessed from the front. At this time I'm just happy to see how well it works and later I'll see if I can communicate with it somehow. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/CGBA_zpsd4rricto.jpg _______________________________________________ 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.