Posted by Jordi Muñoz on December 2, 2009 at 2:00pm
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!
Jordi,
I am an Extra class ham radio operator N8TV. I have built and maintained 2.4ghz video repeaters.
I own a wireless 2.4ghz broadband system UpHi.net.
So I know a little about Db's,amps,TX's, etc.
I may be able to help in this area.
First of all I see some people using 12Db patch antennas. For about the same price you could be using 16Dbi Omni antennas. Then no need to point ! Also put amp at the antenna with power supply. The longer antenna cable from your TX will attenuate the signal enough as to NOT overdrive the amp (a bad thing, it distorts the signal) plus you don't need to worry about pointing the antenna.
The biggest reason wireless operators use directional antennas is because with an omni antenna on receive, you need to worry about noise and unwanted signals coming from all directions, so you narrow the beam down to reduce the unwanted signals.
BUT, on transmit you don't have that worry. The concern on transmit is getting the signal to 'increase' in ERP for the receivers far away.(ERP = effective radiated power)
If you could keep the 'beam' or 'patch' antenna pointed the right direction all the time, why not go with a 24Db 'grid' antenna ? (Hard to point!)
The rule for output power is for every 3Db increase in power the ERP doubles.
So, 500mw power is 27Db. Now add 27DB plus a 16Db antenna you have an ERP of 43 DB.
Thats like 12 WATTS of ERP ! That will reach a LONG way. I have data links of 20 MILES with that kind of power !
So, Jordi's amp at 500mw WILL increase your range substantially, especially with a good patch or hi gain omni antenna.
@Skyler, the connector have a golden nut to hold it in place.
@Doug, i'm using 1.3Ghz video and Remzibi OSD for telemetry in the same video link and 2.4Ghz... No 900mhz... I have to be careful with the 1.3Ghz to void interference to the GPS. But it works.. ;-)
Here are a few things to consider when using Spektrum transmitters with a booster.
1) The DX6i has two power output levels: Europen (~100mw) and USA (~200mw)
2) The DX5e has no adjustable power levels because it is not programmable. The output could maybe be between 100mw and 200mw. Who knows?
3) The input to the 500mw booster that Jordi is selling can only handle 20dbm which is 100mw.
4) Therefore if you are using a DX6i, set the transmitter to the 100mw level and use a long coax cable between the transmitter and booster as Jordi has recommended.
5) If you are using the DX5e, you might be overdriving the booster possibly causing it to shutdown on overload. This is something to consider. The DX5e is nothing like the DX6i.
Greetings Olivier, I see were you drilled the hole to install the {pig tail cabel} ? I can kinda see what this is,it seems the antenna threads onto it. When you drill the hole how do you install it? Does it hook up to anything or do you just insert it and thats it? Were did you get the pig tail you installed in the drilled hole?
The link will disappear or show up as longhand text if done incorrectly.
First select the URL from the source and then moving to the comment area, highlight a word in the sentence like maybe the company name, etc, then press the link icon in the bar, and paste the URL in the drop down window that opens. Works everytime that way.
@Jordi - sorry for the question on the side, but I'm remembering posts in the early ArduPilot days of mixing/matching comm links - 72MHz RC, 900MHz XBee & 2.4 GHz video. If you've switched to 2.4 GHz RC link, what are you running for XBee and Video comms? I run 2.4 GHz RC alongside 2.4 GHz XBee, but have never really done enough to make sure I am not/will not get interference.
By the way, this booster setup rocks.
Ok, it can't be the 6v regulator (measurements are good). The replacement pig tail cabel can't be it because of the fact, wen i put the antenna straight on (without the booster) it will work properly. It has to be the booster, but on the network router it will increase the range enormous... The only think i can imagine, is that the combination don't mach between the rc tx and the booster :(
I had tried to place an url of the booster i have purchased but i don't see him. Here it is for the second time, wen it works! www.dealextreme.com/details.dx/sku.28711
I have the same spektrum dx5e, and i'm trying to get it work.
I have drilled a hole to fix a pick tail cabel in it. (no soldering required) i'm using a 500 mw booster
As 6v regulator i use the same as shown above.
But it doesn't work !!! When i switch to the range check function, i can nearly walk 10 meters away....
Maybe its the range check function ? i haven't try to check the range without the range check function on.
Comments
I am an Extra class ham radio operator N8TV. I have built and maintained 2.4ghz video repeaters.
I own a wireless 2.4ghz broadband system UpHi.net.
So I know a little about Db's,amps,TX's, etc.
I may be able to help in this area.
First of all I see some people using 12Db patch antennas. For about the same price you could be using 16Dbi Omni antennas. Then no need to point ! Also put amp at the antenna with power supply. The longer antenna cable from your TX will attenuate the signal enough as to NOT overdrive the amp (a bad thing, it distorts the signal) plus you don't need to worry about pointing the antenna.
The biggest reason wireless operators use directional antennas is because with an omni antenna on receive, you need to worry about noise and unwanted signals coming from all directions, so you narrow the beam down to reduce the unwanted signals.
BUT, on transmit you don't have that worry. The concern on transmit is getting the signal to 'increase' in ERP for the receivers far away.(ERP = effective radiated power)
If you could keep the 'beam' or 'patch' antenna pointed the right direction all the time, why not go with a 24Db 'grid' antenna ? (Hard to point!)
The rule for output power is for every 3Db increase in power the ERP doubles.
So, 500mw power is 27Db. Now add 27DB plus a 16Db antenna you have an ERP of 43 DB.
Thats like 12 WATTS of ERP ! That will reach a LONG way. I have data links of 20 MILES with that kind of power !
So, Jordi's amp at 500mw WILL increase your range substantially, especially with a good patch or hi gain omni antenna.
$44 is a great price also.
Antennas can be found at
http://www.wlanparts.com/category/antennas/
Also 'pigtails' to convert antenna and radio connections. Cables, etc.
Here is another place,
http://www.flytec-usa.com/procat.cfm?wid=1324
So I hope I have helped and if anyone has questions, I will be happy to answer.
Earl N8TV
Nice one... Another link to my collections! ;-)
@Skyler, the connector have a golden nut to hold it in place.
@Doug, i'm using 1.3Ghz video and Remzibi OSD for telemetry in the same video link and 2.4Ghz... No 900mhz... I have to be careful with the 1.3Ghz to void interference to the GPS. But it works.. ;-)
My spektrum reads fcc id: BRWDAMTX10
"0.128 W = 21.1 dBm (average conducted power)"
Hope this helps...?
Havent tried my booster yet, hoping to get my hands on some RF test equipment soon and see what the G-O is :)
Max
Here are a few things to consider when using Spektrum transmitters with a booster.
1) The DX6i has two power output levels: Europen (~100mw) and USA (~200mw)
2) The DX5e has no adjustable power levels because it is not programmable. The output could maybe be between 100mw and 200mw. Who knows?
3) The input to the 500mw booster that Jordi is selling can only handle 20dbm which is 100mw.
4) Therefore if you are using a DX6i, set the transmitter to the 100mw level and use a long coax cable between the transmitter and booster as Jordi has recommended.
5) If you are using the DX5e, you might be overdriving the booster possibly causing it to shutdown on overload. This is something to consider. The DX5e is nothing like the DX6i.
Just a thought.
Regards,
TCIII
Have you had any luck in the booster working yet?
The link will disappear or show up as longhand text if done incorrectly.
First select the URL from the source and then moving to the comment area, highlight a word in the sentence like maybe the company name, etc, then press the link icon in the bar, and paste the URL in the drop down window that opens. Works everytime that way.
By the way, this booster setup rocks.
I had tried to place an url of the booster i have purchased but i don't see him. Here it is for the second time, wen it works!
www.dealextreme.com/details.dx/sku.28711
I have the same spektrum dx5e, and i'm trying to get it work.
I have drilled a hole to fix a pick tail cabel in it. (no soldering required) i'm using a 500 mw booster
As 6v regulator i use the same as shown above.
But it doesn't work !!! When i switch to the range check function, i can nearly walk 10 meters away....
Maybe its the range check function ? i haven't try to check the range without the range check function on.
some pictures.
IMAG0326.jpgIMAG0327.jpgIMAG0328.jpg
I hope someone can help me..
Greets, Olivier
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