Help IDing and Finding Setup Instructions for eBay GPSDO - Page 1
Forum section: electronics / beginners

author: NT0Z
author_rank: Regular Contributor
timestamp: January 31, 2023, 09:55:02 am
content: Hi, gang,I was gifted a "BG7xxx"-like GPSDO, and I have been having difficulty finding out exactly which model it is and how to set it up.It looks like the rest of the BG7xxx-style GPSDOs in that it's in a silver extruded enclosure with green board ends. On one end are four SMA connectors in a single row (ANT, 1PPS, 10MHz, 10MHz), and on the front are two DB9 connectors (lower left/upper right), plus status lights and a couple of reset pushbuttons.There is no date code or model ID of any kind, and I can't figure out how to remove the unit from the case.I fired it up with a 12-V dc analog brick (unit is rated to 24V) and connected a generic GPS antenna via the usual SMA connector.The 1PPS light flashes at, well, presumably 1 PPS (!), and the ACT light is also flashing.I doubt that I'm getting a signal lock, as the antenna is looking out my basement's casement window and I have no telemetry or signal data from any external control software.The 10-MHz outputs put out a less-than-ideal looking square wave and a perfect sine wave (respectively), and the counter in my Siglint 200-MHz scope reads 10.00000 MHz on each (only out to 5 decimals), which could simply be from an internal TCXO?Speaking of TCXO, the case gets warm, perhaps from XTAL oven inside?I would love to know how to set this up, connect the external monitoring software, etc, as my old HP counter needs discipline!I have searched, read, and watched endless YouTube vids, and now I know enough to only be dangerous...Any help will be appreciated,--Kirk, NT0Z

author: NT0Z
author_rank: Regular Contributor
timestamp: February 02, 2023, 01:01:21 am
content: OP Update:Figured out Lady Heather enough to persuade the unit to "talk." After 12 hours the init process is 20% complete.I wonder how Leo Bodnar gets his GPSDOs to lock in 10-20 minutes?The system has pinpointed my geographical coordinates and has mapped sun, moon and a bunch of GPS birds, so I think it's doing its thing.The ACT LED is still solid amber (it was flashing at the onset), and some have suggested that it will be solid green when the 10-MHz lock is achieved.My indicated local time is an hour off, so I may have reversed my local/daylight time switch in the cfg file. Will check.Seems to be doing its thing!Regards,Kirk, NT0Z

author: xrunner
author_rank: Super Contributor
timestamp: February 02, 2023, 01:15:08 am
content: Quote from: NT0Z on January 31, 2023, 09:55:02 amI have a BG7TBL 2017-10-09It doesn't require a "set up". It just works. It locks in about 5 minutes or less after applying 12V power. Antenna is inside a one story house sitting on top of another piece of kit. Outputs a very accurate 10 MHz sine wave. You can get NMEA data from the serial port, but you don't have to.

author: NT0Z
author_rank: Regular Contributor
timestamp: February 02, 2023, 02:52:53 am
content: Yes, some units, especially newer ones with better GPS receivers, lock in a few minutes.This one, with a crappy antenna (plus placement, for the moment), typically takes 1-2 days to square itself away. An outdoor marine GPS antenna mounted atop the house would speed that up a lot.The unit's previous owner, who upgraded to a Leo Bodnar "lock in 5 minutes" unit, said it took 2 days to stabilize after a cold start. I guess that's why he suggested running it with a UPS to back it up during outages.But -- fingers crossed -- once locked the 10-MHz ref signal is golden.Thanks,Kirk, NT0Z

author: NT0Z
author_rank: Regular Contributor
timestamp: February 04, 2023, 10:24:07 am
content: OP Update 2:Well, after 51 hours, the system locked.It loses lock for a while if it can't see any satellites that provide a big enough signal (as measured by the C/N ratio displayed for each sat).I haven't measured the output yet, but I do notice that there's no discernible "lock" indication on the external LED status lights."dc power" is solid whenever power is applied."1PPS" blinks red at 1PPS all the time."ACT left" glows solid amber, but sometimes blinks amber (no correlation so far with Lady Heather's lock/unlock status)."ACT right" blinks red at about 2 PPS no matter what.I still need to get an antenna outsideAnd if I need to connect a PC to the box to receive an indication of "lock" status when it's time to discipline a piece of test gear, I guess I can deal with that. Still, it would be handy to have some external indication, or to understand exactly what the status lights on this unusual unit actually indicate.Regards,Kirk, NT0Z

author: NT0Z
author_rank: Regular Contributor
timestamp: February 11, 2023, 11:46:42 pm
content: OP Update:After installing an outdoor active GPS antenna with a relatively clear view of the sky, even with 55 feet of RG-6 feed line, I now get solid signals from at least 7 sats at all times. Lady Heather says the GPSDO remains locked now, and doesn't drop out of lock when no sats are in view (problem with initial indoor antenna).I still don't know the make and model, and I still can't correlate the behavior of two of the front panel status LEDs, but if LH says it's locked, I'll go with it.Regards,Kirk, NT0Z