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Thread: EXUHF Range issues with various VAS antennas

  1. #1
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    EXUHF Range issues with various VAS antennas

    Using EZUHF 500mw TX(box type) and Diversity receiver on Volantex Ranger EX, with VTX out one wing, LRS receiver out the other (1+ meter separation). Have tried these antenna combos with disappointing range results (flying level at 400ft in populated suburban area):

    Diamond TX and stock monos on Receiver - 1 mile and change before Failsafe
    Diamond TX and VAS turnstile/mono on Rec - not much better (both antenna horizontal)
    VAS dipole TX and VAS turnstile/mono on Rec - still maybe a little over 1 mile (both horizontal)
    Diamond (vertical) on TX and vertical VAS dipole/mono on Rec - 2.5 miles
    Diamond (vertical) on TX and vertical VAS dipole/horizontal VAS turnstile on Rec - 2.5 miles

    seems the vertical Diamond/ dipole was best, but still limited to far less range than others report. What's my next step?

    BTW, using VAS madmushrooms on 1.3 VTX and VRec (Partom 800 mw). Video gets choppy starting at 2 miles and starts cutting out completely around 2.5 to 3 miles. I put the Vid Rec on top of truck cab and stand maybe 4-5 feet away with TX.
    Video interference is real sensitive to my TX position. Bought a VAS 433/1.3 Notch filter and put under my Diamond, didnt help much then it broke! Alex, those need better structural support. I resoldered and put thick coat of epoxy both sides of vertical section....will try it again.

  2. #2
    I read that the exuhf recievers sometimes come with bad soldering on the board which causes bad range issues.. YouTube and you'll find the tutorial

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    Quote Originally Posted by Jasonext1 View Post
    I read that the exuhf recievers sometimes come with bad soldering on the board which causes bad range issues.. YouTube and you'll find the tutorial
    Thanks for the tip. I touched up the TX soldering. If that solves my issues Iíll be very happy. Iíll try it out today.

  4. #4
    Flyer of the lands Hoss's Avatar
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    Make sure you've got good separation between your vtx and control RX on the aircraft first. A foot is probably not enough. This is the most common issue for range with these 2 frequencies. I've gone 8 inches and failsafe'd within a couple hundred feet before. Moving it to about a foot and a half of separation increased that greatly to still have a strong signal 10 miles away. The more separation, the better.

    Edit: just re-read your post - you've got good separation already. I'd try the dl antenna or another receiver.

    Make sure you're not too close to your ground station - this won't affect control range, but will affect video range with 1.3. 433 produces a harmonic in the 1.3ghz range - 433x3=1299, so if you're flying 1280 or 1258, there is a tremendous amount of crosstalk. Separation is the only solution. There are notch filters and such, but they only help so much.

    The dragon link dipole is the best 433 dipole that you'll find and give you the best range of most available antennas.



    Scott

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    Co-Pilot doobie's Avatar
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    can that dragonlink dipole be used on the tx also hoss?
    flyin HIGH

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    Flyer of the lands Hoss's Avatar
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    Quote Originally Posted by doobie View Post
    can that dragonlink dipole be used on the tx also hoss?
    It can, but I wouldn't. Now that I read your post a little more slowly (sorry) I see that you've already tried a pretty good combo in the diamond and vas dipole. You should get miles and miles with that combo. You're going to get a cleaner and slightly more powerful signal with the dl antenna on rx, but 2.5 miles and a failsafe means something is wrong on 433. You should have 100% rssi at 2.5 miles, providing that you have a clear line of sight to the aircraft and that there isn't a tremendous amount of noise in the area that is interfering. Have you tested in a separate location?

    Scott

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    Same base location but flew various vectors w same results. Solder touchup on ez tx didn’t change anything btw. Is there a ez way to test tx output?

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    Same base location but flew various vectors w same results. Solder touchup on ez tx didnít change anything btw. Is there a ez way to test tx output?

  9. #9
    Flyer of the lands Hoss's Avatar
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    Quote Originally Posted by CFish View Post
    Same base location but flew various vectors w same results. Solder touchup on ez tx didnít change anything btw. Is there a ez way to test tx output?
    Various vectors or various ezuhf receivers? Vector isn't going to have an effect here. It seems either you're not transmitting at the proper power level (maybe it was powered without an antenna for a period of time in the past and it damaged the tx?), Or something is wrong with the receiver (have you tried more than one receiver?). To test you'd need some equipment. I'm not sure if an rfexplorer would do it or if you'd need some other type of network analyser... Maybe someone better on the testing equipment side could jump in and answer.

    Scott

  10. #10
    Co-Pilot doobie's Avatar
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    are you powering the tx separate? I run mine with a 3s lipo velcroed to the back of my radio.
    flyin HIGH

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