GPS antenna and connector?

[billdz]

I have a cellular tracker that tracks via GPS, LBS, and wifi. There seems to be a problem with GPS. Sometimes I get a good lock with 15 satellites, then a few minutes later it reverts to LBS with 0 satellites seen. My guess is that the GPS antenna does not have a solid connection to the PCB. The patch antenna is soldered to a small board that connects to the main board via a short cable with a connector on the main board end. I've never seen a connector like this, I can swivel it back and forth but it does not pull out, at least not with the modest amount of force I used.

Anyone have any idea what might be wrong? I suppose the problem could be totally unrelated to the antenna and connection, that's just my guess. I don't have a schematic or any firther info about the device. The loose red wire is labeled as the wifi antenna.

 

[waltr]

The problem could be in several places.

1- could be in the coax where it is soldered to the GPS antenna. The insulation between shield and center could have been overheated and sometimes shorts.
2- Could be a connection internal in the GPS antenna. These antennas can separate from rough handling (rocket thrust and landings). Cris from Eggtimer recommends epoxy between the tan plastic part and the PCB to help prevent internal breakage.
3- could be the coax connector.

Not sure what you can do.

 

[watheyak]

https://www.digikey.com/en/product-highlight/a/amphenol-rf-division/micro-miniature
The last time I came across one of those connectors was on a BigRedBee GPS antenna. It ended up being a U.FL

They score very high on the fiddly spectrum.

 

[FredA]

They score very high on the fiddly spectrum.

They also score very LOW on the insertion durability.
Many are good for about 10, yes 10, insertions before they start to degrade.
I've seen some rated as low as SEVEN.
Tread lightly - don't fiddle with at all unless necessary.

 

[cerving]

I think waltr got it with #1, it looks like the cable insulation is shorted. If you can, replace the u.FL cable, and once you're sure that it's working use some hot melt glue to hold the connector in place on the board. u.FL's don't like movement... rocketry is not the best application for them.

 

[billdz]

I think waltr got it with #1, it looks like the cable insulation is shorted. If you can, replace the u.FL cable, and once you're sure that it's working use some hot melt glue to hold the connector in place on the board. u.FL's don't like movement... rocketry is not the best application for them.

You're probably right, and I don't think I could replace that tiny cable, the photo is an enlargement. It looks to me like the center conductor is soldered to a pin on the lower right side of the board, and the shield is soldered to the ground bus at the bottom of the board. I also see what could be a stray wire in the yellow circle.

 

[FredA]

I also see what could be a stray wire in the yellow circle.

Agree with bill - hard to tell from the photo, but that coax solder job looks wonky

 

[Grog6]

That looks like an SMB cable; they have great retention. Fred is right, they're good for only a few insertions.
Grasp the metal connector firmly with fine needlenose, pull hard and it will come out. There's a ring-spring holding it in.