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477Re: [RTrak] rtrak-hab onboard power

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  • Jason KG4WSV
    Apr 11, 2014

      On Fri, Apr 11, 2014 at 12:00 PM, Barry Sloan <bs@...> wrote:
      >
      > I believe 3.3V is only used for the GPS so should be ok to remove the reg. (which is probably the easiest way to un-power the GPS without cutting a trace).


      Removing the Copernicus works, too.  I wondered if the copernicus used an internal rechargeable battery (for battery-backed RAM storage, e.g. almanac data) that had gone bad and was causing my problems, so I removed one and opened it up.  No battery.

      > Guess you weren’t able to solve your antenna issues

      Nope.  I thought you were right; the first unit I inspected had very rough looking coax at the antenna can.  I opened it up, installed a new, longer piece of RG174 with a factory crimped SMA.  Took it outside and it locked within a few minutes, as expected.

      Thinking this was the solution to the problem, I spent the next few hours doing the same to the other units, and remounting the antennas and adding hot glue to strain relieve the coax.  Took all 4 units outside - and nothing worked, not even the one that had worked a few hours previously.

      I did run a test with all 4 units, and they work as expected if I plug a Garmin GPS18 into the GPS connector.  I just rebuilt one by removing the copernicus and installing a cable for the GPS18.  Hopefully there's enough heat sink provided by the PCB so that the extra 90mA won't kill the regulator.

      > I’ve found the Copernicus GPS as good as any

      This is my only experience with it, and based on that I think it's junk.  These things worked for one flight (or would have worked, if someone hadn't insisted on rigging them upside down, and I can't blame the GPS for not locking when it's looking at dirt) and have never worked since.

      -Jason
      kg4wsv
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