Hi
Great information !!!!! > On Aug 22, 2015, at 11:19 AM, Arthur Dent <golgarfrinc...@gmail.com> wrote: > > "Does anyone have any information or experience with this small > Trimble GPSDO?" > > I had previously posted that what I thought these boards > were and how they might work and said I was waiting for 2 > of these boards that I had ordered to arrive. Yesterday the > 2 boards arrived in an Epacket from China. If you order > more than one board check them carefully on arrival because > the 2 I received were placed back-to-back with no padding > in between and a couple of the small SMD components on the > back side were partially ripped off the pc board. Fortunately > the damage was repairable and both boards are ok. What I found > was that there are at least 2 different versions of this GPSDO > and although both function the same, the location of some > of the parts differ. > > First, there is the understandable language barrier and if > the sellers do have information that could help you get the > board up and running, it isn't included in the English > listings. Some of the info you can glean from looking at all > of the photos of the various units for sale on Ebay is just > from arrows on the photos telling where to connect power and > get the 10Mhz output. It took me a lot of trial and error plus > tracing out some of the runs to get to a point of where the > boards were working as intended. > > The supply voltage required is stated to be 5.6 to 6VDC and > this goes to an LT1764A low dropout regulator set to 5VDC out > so my 'guess' is that 6VDC should be the minimum supply voltage > to make sure the regulator keeps working properly. With the > multicontact connector facing you you will see a 5A fuse near > the back right edge of the connector. I soldered the '+' supply > lead from my power supply (that puts out about 6.3VDC regulated) > to the left end of this fuse and the '-' supply lead to the ground > plane on the left of the connector. Using too high an input VDC > could cause the regulator to dissipate too much heat. How much current does it pull at turn on? The regulator is only rated to 3A so I would *guess* it’s less than that. > > When the board is powered up with the antenna and the 10Mhz > output connected you will see no 10Mhz output. There are two > 2-color LEDs on the board, on top of one version, and on the > bottom of the other version. One is the ALARM LED and the other > is the ACTIVITY LED. On power-up both light red then go out > (if all is well) then the ACT LED stays on solid green for maybe > 10 minutes until the GPS receiver starts to track satellites. At > this point the ACT LED starts to flash a slow green and the 10Mhz > output is turned on. After a few more minutes when the board > achieves lock the ACT LED starts flashing green at a higher rate. > > On the left front corner of the board is the 1 PPS connector. > To the right of that connector are 4 unpopulated holes for a > connector. I traced those out and found 2 went to a RS-232 There’s also this listing that shows an pair of 9 pins tacked on the same board: http://www.ebay.com/itm/Trimble-GPS-Receiver-GPSDO-10MHz-1PPS-GPS-Disciplined-Clock-with-rs232-port-/261997391557?hash=item3d0042eec5 > chip that appears to be a different type depending on which of > the boards you receive. The left hole is ground (RS-232 pin 5 > on the computer end), then the next hole is not connected, then > RS-232 pin 2, then pin 3 being the hole with the square index pad > on the right. Using a terminal emulator program and 57600 8N1N > I was able to communicate with the board. Typing '?' will give > you a long list of all the commands it will accept. For instance, > 'STAT' and 'POSSTAT' are 2 of the commands that will give you > info on how the board is working. Typing *IDN? at the UCCM-P > > prompt returns 57964-60 for my board and POSSTAT shows up to 12 > satellites can be tracked. Time to get a few mods in on LH :)…. > The date code on my unit is 2009. > The board seems to work well but the OCXO runs pretty hot so it > probably isn't a double oven. I think it’s pretty safe to guess that a GPSDO designed well after SA went off for good has a single oven rather than a double oven on it. Bob > The multicontact connector probably > has most of the functions and LED signals available but I couldn't > see using it so I'll get whatever signals I want directly off the > pc board. > > -Arthur > _______________________________________________ > 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.