[time-nuts] Teardown of Chinese made eBay GPS antenna.

Bob kb8tq kb8tq at n1k.org
Wed Mar 28 20:37:07 UTC 2018


Hi

So, after only two months in transit my examples of the “Chinese GPS Antenna” are
here to poke at. They are from www.stotoncn.com <http://www.stotoncn.com/> and are labeled as being their
part number GN-GGB0710. They clearly show 3.3V to 18V as the operating voltage
on the  box they came in and on the antennas. All labeling is in English. It appears 
they will happily sell you as many as you want on AliExpress for ~$67. All data indicates
they will run L1/L2 GPS, Glonass, and Beidu. That is what the labeling on the parts
indicates. There is some conflicting data on the web about L5 operation …. we’lll see 
how that part goes. All packaging, labeling, and QA stickers match what show up in 
pictures on the web site. As best I can tell from Mr Google , they are indeed  legit 3.3V 
to 18V devices.

Bob

> On Feb 22, 2018, at 2:48 PM, John Green <wpxs472 at gmail.com> wrote:
> 
> For those who have been following the saga of the Chinese made, eBay
> purchased antenna that failed, I may have an answer as to why it failed.
> I had to destructively disassemble it. I just could not get it apart any
> other way. I used a Chinese version of a Dremel tool with a metal saw
> blade. After making a huge mess with plastic particles everywhere, it
> revealed a circular FR4 board with two patch antennas mounted, one atop the
> other. I assume the smaller one to be the L1, and the larger to be L2. This
> part looks almost identical to the Trimble Microcentered antenna I worked
> on recently. On the back side of this is a metal shield  about 3 by 3
> inches soldered to the circular FR4 board. I switched to a abrasive wheel
> and took off some of the solder holding the shield to the board. Then,
> using a small screw driver, I went around the shield breaking the solder
> loose. The shield off revealed that the coax goes to some capacitors that
> couple RF out and through an inductor with some capacitors to ground and
> finally to a SOT23-5 package labelled LK33. This appears to be a Micrel
> MIC5203 3.3 volt regulator. It is shorted on the input side. I believe that
> putting anything over 7.5 volts on the input exceeded the power dissipation
> rating and caused it to fail. I plan on wiring up a more robust 3.3 volt
> regulator in its place and trying again. It looks like I will be able to re
> solder the shield back. The watertight integrity is gone for good. I think
> I can find a plastic box I can mount it in so I can at least experiment
> with it. I have sent a message to the seller detailing my findings. The
> Micrel part lists a 20 volt maximum input voltage, so in theory at least,
> this might have worked, and there might be some of these out there that
> don't fail.
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