Long Range RC Radio Project with 2.4 Ghz
There is a few different ways to get more range with an RC radio like the UHF LRS system developed by Thomas
Scherrer and the DragonLink. Both systems have more then 3-7+ miles of
range. Another option is using a J-pole antenna (FM only) in place of
your standard antenna giving 2-3 miles of range. These are all good ways
to gain more range but for me since I mostly use
2.4Ghz RC radios those aren't options. After reading that some FPV
pilots have used 2.4ghz patch antennas and/or WiFi boosters with good
results I decided it was time for me to give it a try. On
recommendations I purchased a Wifi Booster on eBay for under $50 and a
2.4ghz patch. This booster will increase the RC radio power output from
100mw up to 1 watt which if this works will increase the range from 3000
feet to 2 miles...maybe even more.The patch will be used on my antenna tracking station so it will always be pointed at the aircraft for even better range. More on this in the Ground station pages. For
the RC radio I will be using my Futaba 9C with a Spektrum 2.4ghz
module. This should make this mod easier since I won't have to remove
the stock antenna or use a interface cable (SMA to U.FL)
from the circuit board like with Spektrums DX6/7/8 users do. So for
this all I have to do is remove the factory antenna from the Spektrum
module and put the booster with 5db attenuator
A Futaba 9c with Spektrum 2.4ghz module can have the WiFi booster in-line and then reconnecting the factory antenna to the booster.....easy :).
I purchased a HobbyKing UBEC that outputs 5-6 volts placed on the 6
volt setting. This is needed to power the WiFi booster which operates on
6 volts. I connected the BEC to the RC radio battery (12v) to get the
power. In the future I will be adding a master battery power switch so I
can only power the booster when the RC radio gets power....THIS IS IMPORTANT!!!....Do Not Power Up your RC radio with the booster off and/or with antenna disconnected. This will ruin the RC radio.
Radios must have an antenna connected anytime it's on!!! and this info
is in your RC radios manual so the same goes for when there's a booster
attached....if the booster is off, then it will be just like not having a
antenna connected. To keep this from happening always power up the
booster first or do what I'm planning on doing by adding a master
battery switch this way everything will be powered on/off at the same
time. Another concern is the booster has a warning label warning not to
input more then 50mw or damage to the booster may result. The
Futaba/Spektrum radio I'm using has 90-100mw output so to reduce the
input I will add a in-line 5 dB attenuator (3 to 6 dB can be used)that
will decrease the input power of the Spektrum module adding protection.
Note: Some FPV pilots doing this booster mod have reported that the
booster works fine without a attenuator because it's not powered 24-7.
This maybe true but a attenuator is Highly Recommended!!!
when using short extension cables (under 18") and cheap insurance at
less then $20. Without a attenuator you risk ruining your RC radio
and/or the booster. Also if you use a 50 ohm SMA extension cable longer
then 5' to 10' feet it will act like an attenuator so don't use both
together...one or the other. W
With this mod and using the radio
for over a year now... I feel more secure about my RC radio link. Even
though I don't do much long range flying and this mod isn't really long
range like other systems but it's nice knowing I have a more solid link
at 6000+' ...this I really enjoy.
A DX7 Bottom and DX8 (top)
The DX6/7/8 have a U.FL connector at the PCB which needs to be adapted
to a male RP SMA connector so it can connect to a 2.4 ghz WiFi Booster in-line with the antenna.
The DX8 is powered by a 2s lipo so I use a Y cable from the battery to power the UBEC
that in turn powers the booster with 6 volts.
Futaba 9c with Spektrum 2.4ghz module along with booster.
Want to find these items?
Since links may only work for a short time try Searching for the these terms on eBay and the net.
Attenuator: "07-02750 Sertek 5 dB Coaxial DC - 4GHz 5dB
Links: ComputerGeeks.com Dealextreme.com
Forum link : RCgroups.com
How-to DIYdrones link
Update: 3-24-2010: After testing I gained a easy 2500 more feet of LOS range.
Before adding booster the 2.4ghz radio lost contact around 3000-3500'
and now with booster it still had a good solid link at 5500 feet LOS. My
RTH was not working so I did not risk going any further. More long
range flight testing to come.
This mod also works with surface/ground radios. A good idea for FPV driving of larger
RC trucks like the HPI Baja 5b,5t and 5sc.
Update: 1-14-2011: Still working fine and no issues (38 flights). Range is over 1-1/2 miles at 7200 feet tested.
Update: 2-10-2011: Boosted DX8 with same 1 watt booster.Tested and working Fine.Even the telemetry is reporting with the Spektrum data transmitter TM1000 .
Update:11-03-2011:Sold the DX8 and went back to the DX7 and Futaba 9c. The DX8 had Firmware issues that I did not care to keep updating. It had false alarms and blanking out screen problems.
Update:02-15-2012: Purchased a DragonLink LRS. Not sure it's better but does have a solid 6 miles of range which is nice. It took 2 months to arrive and then sent back for Firmware Updates with very poor customer support. Another 2 months for updating. The 2.4 booster never needs any Firmware updates and still works perfect.
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