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Pilot-End Mod Complete

Discussion in 'Phantom 2 Vision + Mods' started by itchybeard, Sep 9, 2014.

  1. itchybeard

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    I have now finished installing my Horizon compact single extreme kit.

    Verdict: An absolutely terrifying experience.

    I was going to photograph the process, but having ruined a pigtail yesterday trying the solder/splice trick, I thought it might be better to concentrate on the job instead.

    Having thought things through, I realised that a soldered splice would create an impedance point, so, I decided to go against Will at Horizon's advice and remove the original RC controller antenna-cable from the board by scraping away the glue. I managed to do it without damaging the connector or the board (whew!). I also managed to source a 180mm pigtail which is an excellent match for 5.8Ghz, as It works out at 5 wavelengths and puts the RP-SMA connector right on the 50 ohm point, excellent.

    My new pigtail arrived this morning. I checked it with my multimeter and fitted it without incident. Then I dismantled my repeater, checked the pigtails supplied by Horizon and carefully fitted them. Drilling the holes in the side of the repeater was quite nerve-wracking, but I got them in exactly the right place.

    Next I fitted the antennae, crossed my fingers and turned on the RC controller. I was relieved to hear the two beeps and get a green light. I turned on the bird and then the repeater and my phone. It all fired up successfully and supplied both telemetry and FPV (Yay!). Next, I checked the RC controller using the RC System Assistant and recalibrated the sticks. I also checked the stick calibration on the bird using the Phantom Assistant. All was well and the IMU didn't need calibrating.

    I decided to take her for a test-flight. The weather was perfect this evening; a clear sky and not a breath of wind. Having done my pre-flight checks, I launched the bird from the bottom field and watched her drift lazily away into the blue. I flew her around line-of-sight for a while and then sent her out a bit further. I was running 640 x 480 @ 15 frames per second (without the booster app), and was up at about 350 ft altitude. The FPV started to get slightly glitchy when I got out to around 3000 feet, which, I thought was quite reasonable considering all the power-lines, trees and buildings in the area. I have never had her further out than 1300 feet before, so, I think we can say that the antenna kit has made a substantial difference. I shall try again tomorrow using the booster app.
     

    Attached Files:

  2. DBS

    DBS

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    Nice... loved the story and the way you tell it :D

    Looks like everything came out solid and doubling your range must be a satisfying reward in itself...

    what booster app are you gonna go with? I hear the Utility App at 17dBm is giving best results :ugeek:
     
  3. itchybeard

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    Hi, DBS.

    I already have a copy of PVFlyer's FPV Booster (V+ Booster) app. I just forgot to run it before I launched the bird this evening.
     
  4. DBS

    DBS

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    His should work well also... you said power lines and buildings in the area so his "interference control" feature will undoubtedly help there.
     
  5. kxkraze

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    Hey DBS,

    You might be able to save me some time here... is the 17 dBm you are referring to in reference to the booster setting, the camera setting, or both?


    Congrats on the antenna upgrade itchybeard. Time to take it out and see how far she'll really go.
    .
     
  6. DBS

    DBS

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    The camera setting...

    I don't use the repeater setting because i run hardware boost on mine so i don't have any answer on that side...

    Plus... the repeater shows in the specs that it puts out 20dBm ... and the highest boost is 20dBm ... so any other "boost" levels would be negative ... unless tuning it back just a bit would clean up the signal a little... i haven't really messed with it though so that's just speculation. :ugeek:
     
  7. kxkraze

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    Cool. Thanks for the reply DBS !!!
     
  8. N017RW

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    Good call on the choice not to 'solder splice' the coaxial cable.

    Always use proper terminations and connectors especially at microwave frequencies.

    You're goal is to improve performance and efficiency.

    Kinda like two steps forward, one step back.

    I know others have done it and it works, yes it works but...

    ... as a Ham I will say it's really something you should only do to 'get off the island' if you know what I mean.
     
  9. rrmccabe

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    Yea but you cant listen to anything a ham would say.

    73,
    kd0zv
     
  10. Gaelmart

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    Hi when you scraped everything off. Was there a proper connecter under there or solder point?. Its my next scary job.
     
  11. itchybeard

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    Hi, Gaelmart

    Yes, when I scraped off the silicone I found a UFL connector underneath. Take your time; take it off in thin layers and be very gentle, I used a modelling knife and tweezers, which worked well for me,

    I wish you the very best of luck.
     
  12. itchybeard

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    Update: I did another range-test this evening.

    I did the "tin-foil mod" first though, because I didn't want to push her out to maximum range and then get a failed RTH due to loss of satellite lock. I used the booster app to boost the FPV signal and then opened the DJI app and found that I already had 8 satellites. By the time I took off I had acquired 10 satellites. Hmmmm, not bad at all.

    I hovered at about 150 feet altitude and turned the video recording on and off a few times. No loss of satellites whatsoever. So, it's obvious that the tin-foil mod has worked for me (another job off the list).

    Anyway, I took her up to 350 feet then flew out over the A1 and put her on a heading towards Cambridge. I lost the control signal at 4230 feet and RTH kicked in (I still had full FPV and telemetry though). So, now I know and I'm well happy. The antenna kit has more than tripled my previous control range. Good job, Horizon!
     
  13. Brammo

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    I have a 120mm U.FL to SMA cable, would you suggest against using this?

    Thanks
     
  14. itchybeard

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    Well, I wouldn't use it myself, Brammo.

    The formula for working out the length is .... 300/f * vf

    So, for 5.8Ghz we have 300/5.8 = 51.7241 millimetres. Then we need to multiply by the velocity factor of the coax cable, which is about 0.69. So, we have 51.7241 * 0.69 = 35.6896 .... Let's call it 36 millimetres and say that is equal to one wavelength at 5.8Ghz.

    See here: http://www.youtube.com/watch?v=CZ2aZB1b ... e=youtu.be

    So, basically the length of your coax (in millimetres) should be divisible by 36 and ideally you are looking for a whole number (although having half a wavelength left over is okay ie. 0.5)

    120 millimetres doesn't work very well at all, does it?

    120/36 = 3.33333333 and that is a mismatch and will cost you some efficiency. Whereas, in my case 180/36 = 5, which is a good match and has given me a big improvement in range.

    I hope this helps.
     
  15. Brammo

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    Thank you for the explanation, very helpful.
     
  16. slothead

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    Good report itchy. I have one question: When you say "I launched the bird from the bottom field..." what did you mean by the "bottom field?"
     
  17. itchybeard

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    Hi, Slothead

    I am fortunate enough to own a few acres of land in Bedfordshire, UK (no, I'm not a farmer). So I was talking about the field where we keep the horses ;)
     
  18. ToThePoint

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    There is a connector, the same kind as on the RC board when you do a antenna mod there.
    Its a u-fl male i guess.
     
  19. saao

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    Hey bro saw ur kit lools extreme. I was wondering has any one soldered the rpsma bulkhead connector to the rc 5.8bghz wire. Like cut the dipole and just solder no removing glue or no splicing
     
  20. itchybeard

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    Yes, Saao, that is the way that Horizon FPV recommends. The soldering mod for the RC controller is explained in their video. It starts at about 12:50 - see here ....

    https://www.youtube.com/watch?v=CZ2aZB1bakU

    However. I really don't think it is a very good way to do the mod. It's a bodge job and will probably introduce a resistance point into the cable, which would throw out the calculation for wavelength. It could also take the resistance at the RP-SMA connector to more than the required 50 ohms.

    Also, I don't think the "soldered splice method" is any easier than the "glue removal method". The coax cable is incredibly thin and stripping it to reveal the centre cable and the shielding and then soldering the delicate wires together would be very difficult even if you had all the right equipment.

    Both methods are quite risky and require a delicate touch, but the glue removal method gives you a better connection; a cleaner finish and also allows you to upgrade the cable whenever you want.

    The choice is yours. Good luck.