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Thread: Antenna Problems

  1. #1
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    Antenna Problems

    Hi there,

    Bought a 16 turn helical antenna (one of the video aerial system super cannons) to replace my cheapy 7 turn aomway helical which to its credit did 8.4km on 5.8ghz on the ground station.

    However, this new antenna is quite frankly awful, it literally takes about 50m before going out of range. Gone through all the usual suspects such as wrong polarity, swapped the receivers around even went as far as buying a huge video lead to get my dragonlink as far away as possible from it (thought it was more prone to interference) but that was a no go too. I know its highly directional so have the eagle eyes doing the antenna tracking for me which I know to work flawlessly. I did try emailing VAS last week but haven't heard back, so thought I would try here to see if anyone has any input to this! Have my Skywalker doing an hour plus in the air so want to do some sight seeing and would really rather not go back to the 7 turn.

    Somewhat miffed as to its poor performance so been sat with a hobby knife cutting away at the hot glue to see if its some soldering issue. Found a suspect pretty quickly, as the antenna element itself that is soldered onto the core of the coax has a bloody great big blob of solder and is touching the reflector as well as the coax core. Maybe completely barking up the wrong tree with this, but i've eliminated everything apart from the antenna at this point so everything is pointing towards it at fault. I've had the old man look at it as well, who did soldering in the air force (worked with radar) and he instantly said its shorted.

    I've attached a photo of the blob of solder on this, other thing from watching videos by Andrew Mcneil who does some pretty awesome videos on antenna builds is an impedance mismatch which I don't see on this antenna (may well not need it as the build quality looks pretty good - apart from it not working of course!) as he puts a lump of copper on the end to bring it down to 50 ohms.

    Have my desoldering braid ready to rumble but don't want to bust it further if it looks okay to the experts!

    Thanks in advance.
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  2. #2
    Engineer for Jesus Christ IBCrazy's Avatar
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    Email me your address. I will replace it.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  3. #3
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    Thanks Alex - email sent!

  4. #4
    Co-Pilot doobie's Avatar
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    cant beat VAS support
    flyin HIGH

  5. #5
    Instructor Pilot Channel 1's Avatar
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    Quote Originally Posted by doobie View Post
    cant beat VAS support
    Cannot beat their design quality either, I have tested a number of antennas and VAS has some of the best "flat lined" across the designed bandwidth SWR matches I have tested.

    Now SWR is not a major problem at lower power, but I commonly run 2 to 7 watts to maintain a excellent fade margin and a high SWR (1.5+) can give me problems with the PA design.

    Wayne
    Everybody loves a bunny.

  6. #6
    Co-Pilot doobie's Avatar
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    ya I swear by VAS. my FPV buddy zacattack brought me his 2.4 pepperbox over last winter to try for couple weeks and I tell ya, I fell in luv!!!! I bought one of my own I was so impressed. I tell everyone it's hands down the best $100 bucks ive spent in FPV. currently using circular wireless CP on my vtx's but I keep an eye out for used madmushrooms to replace them LMAO
    flyin HIGH

  7. #7
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    Had these shipped over to the UK via RMRC, VAS has a great name here over the pond too (the other 2 long range FPV'ers in my club both swear by them for good reason). but finding a supplier with some in stock is a challenge (think there are two retailers for VAS in the UK - both were out of stock when I wanted to burn some FPV cash!).I bought a mad mushroom at the same time as the helical for the VTX and its performance compared to the aomway cloverleaf I had prior is like night and day, had nearly an extra km out of it with the same cloverleaf on the receiver.

  8. #8
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    Just an update on this, I desoldered the blob of solder, followed by re-soldering and layering hot glue between the reflector plate and the antenna element. And problem solved, got out to 9km with good video still!

  9. #9
    Co-Pilot doobie's Avatar
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    good news mate!!! enjoy
    flyin HIGH

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