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IMPORTANT note when upgrading wifi antennas!

Discussion in 'Phantom 2 Vision + Discussion' started by UKFlyer, Aug 31, 2014.

  1. UKFlyer

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    Good day all, i installed the stage 2 antenna kit yesterday from fpvlr which involved opening up the wifi extender to fit the 2 sma cables to the board, the flight i had yesterday was my best with the fvp at the highest preview setting and the whole flight was flawless. Today i went out for a flight and during the pre-flight check i see the radar is pointing kind of north west although i am directly behind it so it should be pointing north. ( 9 sats and all is ready to go) I backed out the app, went back in and still the same so i uninstalled the app, installed it and still exactly the same so i decided not to fly.
    Back home i thought i'd check the wifi extender sma cables i fitted because i knew they were both close to a metal case on the board but there was a slight gap on both when i screwed it back together, on opening up i see one of the cables is actually touching the metal casing so i realize the one must have moved and now touching, It was a tight fit when i installed them yesterday and was not really happy leaving such a small gap, you see the stock ones come in from the opposite side of the board and have no chance of ever making contact with the metal.
    I then cut away some plastic casing either side of the extender so that i could route them to run on the outside of the circuit board, now totally secure with no way of the cables moving because it is behind the plastic i'm happy.
    As soon as i opened the app the radar was perfect and totally true as i already had gps lock, the two flights i had today were flawless and the radar showing true position all the way. :D
    So the moral of this story is, MAKE SURE THE SMA CABLES ARE SECURE AND NOT TOUCHING THE METAL CASING AS THIS CAN CAUSE INTERFERENCE!

    The first time i fitted them and the wrong way to do it.
    [​IMG]

    Much better.
    [​IMG]

    This may help if you are thinking of upgrading the antennas in the wifi extender or if you have already done it maybe recheck connections and make sure there is no way they could touch the metal.
    While on the subject i see my wifi extender had shielding between the circuit board and stock antenna but in the videos on youtube there is non to be seen, is this something dji implemented with the vision+'s manafactured at a later date?
     
  2. DaveMoi

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    I dont understand why it should matter that they touch, they're both negative...
     
  3. itchybeard

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    Hi UKFlyer

    The same thing happened to me with a completely stock setup (I use a Galaxy Note 3 for FPV). The bird was pointing south and I was standing right behind it. I had 8 satellites and had already calibrated the compass on the bird, but the arrow on my radar was pointing west.

    I cured the problem by recalibrating the compass on my Note 3.

    https://www.youtube.com/watch?v=fYQr9kw8IJw
     
  4. UKFlyer

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    Not sure why the radar is perfect now then after i moved them? the stock ones have no way of touching the metal as they are routed the other way. :?:
     
  5. UKFlyer

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    I forgot to say, the first thing i done was recalibrate the compass (twice) and the process was successful on both occasions, radar remained exactly the same.
     
  6. DBS

    DBS

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    I agree... Both the outer shield on the u.fl connector and the metal casing over the wifi module are connected to the same ground shared throughout that entire pc board...

    But even if it did cause interference it would be wifi interference maybe affecting video stream... But why would it affect compass heading? :?

    Probly had a compass problem that fixed itself and the fact that you moved your cable was just a coincidence... My stock cables were touching the metal casing and never had any compass problems before or after my SMA connector mod :ugeek:
     
  7. itchybeard

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    Indeed, but perhaps you moved your phone/pad around while you were stripping and reassembling your wi-fi repeater and that recalibrated it.

    The compass on the bird and the phone both have to be calibrated correctly in order for the radar to give a correct reading.
     
  8. UKFlyer

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    I was in a different location with my phone when i stripped/reassembled so this could be true, Its also only my second day with the Galaxy S5 so maybe the phone was kind odf sorting itself out? I'll see how it goes.
     
  9. itchybeard

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    I have noticed that my Galaxy's compass goes out-of-whack quite easily, it's certainly worth keeping an eye on. I calibrate the phone every time I fly nowadays ;)
     
  10. lignow

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    Thanks, U K F I will have a look at mine.
     
  11. UKFlyer

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  12. UKFlyer

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    I noticed as well there was no sheilding in the video but mine has got it between the circuit board and stock antenna, this is why i asked if this was someting dji implemented at a later date? Anyone else does/not have sheilding in the extender? :?:
     
  13. UKFlyer

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    I left my sheilding in although with hindsight there is no need for it as the stock antenna it is shielding is no longer used.
     
  14. Luap

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    Mine has no shieldind its th RE500. Think RE700 has the shields