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Thread: Poor Range with Crossfire?

  1. #51
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    That picture comes from the support article Perna linked to just above my post. How I interpret this, it's more than a balun.

    As far as power goes, I've scoped it out. My VBatt power rail is already mighty stable, thanks to 220uF low-ESR caps on all ESCs, plus I'm using the mPB from BrainFPV, which has capacitance and LC filtering before the 5V reg. 5V is pretty much a flat line here, apart from the 1200KHz switching noise, which is maybe 20mV peak to peak.

    --edit: You might be right anyway. I measured the black part on a broken antenna (after scraping off some of the paint), and there's continuity to ground, but nothing to the antenna pin.
    Last edited by Glowtape; 15th May 2017 at 12:13 PM.

  2. #52
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    For best antenna orientation try to fit following requirements.
    Parts labeled with "Antenna" below should be:
    - Separated as much as possible from any carbon or conductive material
    - Separated from the wire going to the receiver
    - As straight as possible

    I stand corrected. Below that picture in the document they have it mounted as a V shape in a Vendetta. Time to get the 3d printer back out and make some sort of V shaped drink straw holder.

    Are you also using a BrainFPV RE-1? Thats what I have in the QAV-X along with the micro vector. That controller and its PDB are amazing.

  3. #53
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    I had an RE1, which I broke while scoping some interrupt lines to diagnose a source of jitter in the firmware. I'm running a Seppuku from AirDTF now.

  4. #54
    Quote Originally Posted by Glowtape View Post
    This one is interesting:



    Kind of throws a spanner into my current setup with the PTFE tube. Because as per image posted on the top of this page, I evidently have the wire running parallel and right next to the ground part of the antenna. I guess this explains a lot of my issues. The wire part picking up an inverted version of the signal the ground part gets, cancelling each other out.

    I guess I have to try the V-shape, and consider changes to by upcoming frame to mount it straight (holes through both top and bottom plates, PITA to take off though).
    When it comes to antennas an antenna end connected to ground is not equal to ground. It's also an active antenna element (see link below). This is why it has to be exposed too. When you align the black antenna element from the picture above with the wire going to the receiver you absorb most of the signal which decrease your range a lot. It's almost the same if you would remove it completely.
    https://en.wikipedia.org/wiki/Antenn...x394x150ms.gif

  5. #55
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    Quote Originally Posted by Perna View Post
    When it comes to antennas .....
    So what is the proper way to mount the antenna? In your above statement it sounds like you are saying do not run the black wire labeled "antenna" in the picture above next to / parallel with the black wire labeled "wire".

    Do the two elements - the black wire labeled "antenna" running horizontally left on the picture above - and the silver element labeled "antenna" on the right in the picture above - need to be 180 degrees apart?

    A few pictures of the mounting of the antenna on whatever copter you used to design and test this antenna would be really helpful.

    Thanks!

  6. #56
    Quote Originally Posted by DWB80117 View Post
    So what is the proper way to mount the antenna? In your above statement it sounds like you are saying do not run the black wire labeled "antenna" in the picture above next to / parallel with the black wire labeled "wire".

    Do the two elements - the black wire labeled "antenna" running horizontally left on the picture above - and the silver element labeled "antenna" on the right in the picture above - need to be 180 degrees apart?

    A few pictures of the mounting of the antenna on whatever copter you used to design and test this antenna would be really helpful.

    Thanks!
    This is a good mounting option.

    Click image for larger version. 

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  7. #57
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    Oh yeah, pulled it out of the tube and did a 90 V with zipties, without the wire from the RX running parallel to anything. RSSI went from around -45dBm to -32dBm on the bench, and SNR also seems 11-13dB higher.

  8. #58
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    Can confirm! By running the silver lead vertically up thru a drink straw and the black wire the opposite direction downward - tying it to the frame - its not even perfectly straight going down - I see similar results on the bench - at least a -15dB gain. Letting the black wire run perpendicular to the silver wire gave similar results.

    More good news, can walk indoors and through walls from one end of the building to the other and the power stays at cool 10mw. The TX power level no longer jumps around.

  9. #59
    Great! So we probably found the root source of your range issues?

  10. #60
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    I think what we did was get even more range. I had no problems at all in the field i fly in. No problems going 900 feet (275m) with 2 different copters both with Micro Rx's. Never once had a failsafe fire off. The only thing I would see / hear is the Crossfire transmitter bumping up the power occasionally at close in distances. Im using a 1st gen Taranis and it has some pretty awful audio noise rejection circuitry so when the Crossfire gets up to 500mw the buzzing is audible. The EZ Uhf tx would do the same buzzing until I isolated the transmitter using well placed anti-static packaging around the transmitter and antenna load. Now that the micro antenna parts are separated the close in power fluctuations seems to have ceased - will test in the field as soon as good weather rolls in. Thanks for all the help!

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