I love my Spektrum Dx7 and my 2.4Ghz JR XPS9303 and i refused to trade its solid rock performance by a 72mhz radio just to increase range of my FPV/UAV. So in collaboration with my friend JB we find out the cheapest and secure way to amplify the signal, it even works in some Futabas and virtually with any 2.4Ghz radio, but some modifications are required. Lets see some options:-Spektrum Dx7 this is the cheapest solution for a very reliable 2.4Ghz radio, i used it for about a year and i never had any signal glitch (unless i fly beyond 2000 feet). The problem with this one is that you have to modify it, you need a SMD to U.FL adapter, drill a hole in the side of your radio and just connect and screw the adapter, no soldering required. If you have more than 5 hours of experience with Legos your qualified to do this job. Then you just need to connect the booster. The one in the picture (middle) is already modified.-If you have the awesome JR radio but is 72Mhz you can buy the Spektrum 2.4Ghz module and just insert it in the back of your TX, personally this is my favorite setup. It's a good deal because includes a $99 dlls receiver for free! Note that JR TX alone cost around $600 dlls, but you can get it for less, i got mine for 300 bucks with Spektrum Module included on R/C Groups =P. Remember you are looking for the JR XPS9303.If you have one of the fallowing Futaba radios:7U Series Radios8U Series Radios8J Series Radios9C Series Radios9Z Series RadiosFN Series RadiosYou can just go and buy the Spektrum 2.4Ghz module, easy and with no hassles. It's also a good deal because includes a $99 dlls receiver for free!

One of the advantages of the Spektrum receivers is the build in diversity system, you can even buy one with 4 satellites like this one, or buy a super tiny, tiny setup like this one, or the traditional one.The diversity is crucial to have a reliable link when you are flying far away, also Spektrum has a receiver for Carbon Fiber airplanes (Carbon Fiber blocks RF signals).The idea is to have the best reliable hardware with an SMA connector and the SMA extension cable, after that you are ready for the final step: Get an amplifier. But we are talking about a few hundred dollars here, if you get the weakest one of 100mW it will cost you around $150 dlls. This is not pocket friendly in my point of view. So again our Asians friends come to the rescue, after making some research around the net I've found on eBay and a home Wireless Amplifier, so i decided to give it a chance and i bought it for 60 bucks including shipping! Wow that's a good deal! The one i got is this one.Note that the amplifier needs 6Volts to work, you can get a cheap 6V power regulator from here and just make the adapter. A 3 Cell LIPO is enough to supply it for a long time.

After receiving the AMP i did some tests, here are my results:Before using the amplifier, i was able to fly around 3000 feet away (~1 km) using a 900Mhz@500mW Video transmitter. I never lost the video signal, only the radio link...Using a 1.3Ghz@1Watt Video transmitter i was unable to fly more than 2000 feet away (~600meters). So the 1.3Ghz Video transmitter reduces my 2.4Ghz Spektrum range...Then i got my cheap Asian amplifier and using a 2.4Ghz Patch Antenna i was able to fly around 2.6 miles (4.18Km) away without a single glitch, but i was unable to continue because now my video was causing me problems, hehe!Not bad at all! Honestly i don't need more than 2 miles of coverage, is really a long way for an EasyStar. In conclusion the maximum range for my setup still unknown, but the range achieved is more that 2.6 miles and the +2 extra miles of coverage gained for less than $100 dlls is really a good deal for me!

Now just remember this:-The range will be different in other setups.-Never turn on your radio without antenna.-Never turn on the Amplifier without antenna.-Note that in some country's this amplifier may be illegal.Thanks for watching!
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  • Some of the Spektrum radios (definitely the DX9) can have their power output switched from high (for the US) to low (for the EU). 

    This could help reduce the power going into the amp, and possibly reduce the chances of ti burning up.

  • thanks Flying High, will check out that person.

    yeah I wish to design the antenna from scratch to learn the concept and have more control over the design parameters. 
    there is no video involved yet. 

  • Looking at the specs, it just seems to be the main board, from a 2w wifi amp, shrink wrapped, with the large, stock heatsink removed.

    See here:

    Same price, nearly same specs.

    I have the ebay model. Both work fine for boosting 2.4ghz range. However, I would be afraid of the compact version burning out. Even the 1watt models have a reputation for burning up, probably because our R/C radios push the maximum allowed input current (approx 100mw).

    I use one of these now. Commercial grade and cost over 4x as much, but not likely to leave me hanging with a burnt out amp.

  • anyone have an experience with these:

  • You could build one, but buying one is cheaper than the parts, for 2.4ghz ants.

    There are plenty of free online calculators, for determining element lengths.

    Also, Alex Greve (aka IBCrazy) on RC Groups forums, has posted tons of info on building your own antennas for FPV.

    I've been using 2.4ghz control for about 5 years now. Works great, with and without boosting. I'm also experimenting with some 433mhz UHF systems as well.

    The other factor that you should figure, is what frequency are you using for video? Right now, I use 910 mhz for video, with circular polarized cloverleaf antennas, and 2.4ghz, for control, with vertically polarized omni antennas. The VTX is outfitted with a low-pass filter, to cut out upper harmonics that could interfere with the RX or the GPS.

  • i'm sorry yes this has gone a bit off topic. i plan to build my own transmitter and haven't figured out at what frequency i would be transmitting. i have only rudimentary knowledge of antennae design but have worked a lot on power amps. 

    do you think the 6 db mag mount you are using can be built at an amateur level? i wanted to go more into designing than just purchasing products and plugging them in. works for others, but i wanted something different. 

  • What frequency are you using? This thread was about 2.4ghz boosters and antennae. I am a licensed HAM and have a lot of experience with antenna building and using linear amps.

  • Sgt Ric thanks for your suggestion. I have read the same about power boosters.

    Any antennae in your mind? I have to send pulses at low frequency over the said distance.

    Thanks and regards

  • I've gone 5 miles without a booster, while still getting the telemetry signal back from the RX.

    For short range flights (less than 5 miles), a mag mount 6db antenna, works fine.

    On my boosted rig, I've upgraded to a high quality 500 mw Hyperlink WiFi booster. Much less noise than the cheapo ones.

  • Moderator

    Two kms is easily achieved using the new gen of antennae.

    Power boosters are not the ideal way to boost range since it introduces a whole host of RF noise problems and freq incompatibilities.

    Again, the best solution is high quality antennas NOT overboosting the TX signal.

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