Low cost ($60) 2.4 G Computer Transmitter with Dual Receiver antenna question...


I just purchased this low cost 2.4 G Computer Trasmitter/Dual Receiver that is cheap because it does not have the LCD, etc. adjustments built in, but uses your computer to set up and change the settings. It's seems similar to the FASST or Spektrum. (Here is another place to get it from)

Of course I promptly broke off the small (about 2 inches) antenna wire on the receiver. My question, before I solder it back: can I add a longer length antenna to replace the broken one (since I will need to take it apart anyway) so I can potentially increase range? If yes, it would increase range, how long of an antenna should I make (between 5-12 inches)?

Thank you,


Views: 2407

Comment by James Cohen on June 6, 2009 at 1:16am
Hi Tom,

$60 sounds like a steal, it'd be good to hear how it performs.

Antennas work best when their length is matched to the frequency they're working on (transmitters tend to be more sensitive . Doing some quick calculations for 2.4GHz shows that a half-wave is about 2.5 inches.

Full wave:
30000 / 2400 = 12.5cm = 4.92in

So a half wave is: 6.25cm = 2.46in

Either of those should work.

Comment by Gary Mortimer on June 6, 2009 at 2:01am
Heres a good calculator for antenna length http://www.qsl.net/w4sat/halfvert.htm

Heres a very famous 2.4ghz antenna http://www.saunalahti.fi/elepal/antenna2.html not suitable for this purpose.
Comment by Tom in NOVA on June 6, 2009 at 3:00am
Gary & James.... thanks both. Is there an advantage of having a full-wave instead of half-wave antenna?
Comment by Peter Seddon on June 6, 2009 at 6:35am
I would replace the broken antenna with the same length as at these frequencies it starts to become critical. The length affects the reception pattern as well.


Comment by Mark Colwell on June 6, 2009 at 7:02am
Add a small piece of heat shrink tube after solder repair as a strain relief, to help prevent future breakage, i had same problem with spectrum rx
Comment by Tom in NOVA on June 6, 2009 at 10:53am
Thanks all. I will replace with the same length, but try a little more flexible wire, and also will epoxy it in the opening of the housing to stop it from flexing.
Comment by Tom in NOVA on June 6, 2009 at 11:01am
I was just thinking, if this set up (with the software to adjust the transmitter residing on the computer) would be a good candidate for hacking the software and making it into a laptop/computer controlled remote UAV/airframe. The hacked software would communicate via the transmitter's USB link that is used for programming it, and data streaming in from the UIAV to a groundstation software plattform would be used to achieve not only real-time control of the UAV via the transmitter, but also real-time calibration, and error correction of the controls based on the particular airframe characteristics while in flight

Comment by Thomas J Coyle III on June 6, 2009 at 11:58am

You can use the Endurance RC PCTx (http://www.endurance-rc.com/pctx.html ) along with ServoCommander to control an RC transmitter with a PC. This solution might be cheaper, time and hardware wise, than trying to create software to control the joysticks on the transmitter.

I have two of the Endurance RC PCTxs along with ServoCommander and they work fine with my Spektrum DX6i and Hitec Laser 6.

Just a thought.

Comment by Tom in NOVA on June 6, 2009 at 12:18pm
Thomas. Thanks for the post. It seems Endurance RC PCTx does exactly that, and for not a bad price. Will read more upon it.

Comment by Sami Finnila on June 7, 2009 at 5:50am
You can get this radio for around 30$ from HobbyKing. I myself changed over to Turnigy/iMax 9X radio from my Futaba T6EX FASST radio due to the outrageous prices of Futaba receivers and equipment in general. The Turnigy 9X (actually only 8 channels with 2.4GHz module) with Assan 2.4GHz module and two receivers was only around 160$. So I actually saved some money by changing and got a much more advanced radio with more channels in return. The Assan radios modules (version 2) have been reported to be very reliable (DSSS on two channels (?); just like spectrum) but haven't got to testing my unit yet.

... talking about HobbyKing: they have 3 cell 2200mAh 20C LiPo batteries that cost under 16 bucks. Bought 10 and have been happy with them so far..

I actually ordered almost everything that I'm going to need for this summer's RC flying from HobbyKing and saved almost 700 euros by doing that (while making a 500 eur order). Ofcourse the quality of the equipment I got dropped somewhat also but I don't complain.

Anyways, back to topic! :) This radio is definitely value for the money and I have heard only good things about this radio (actually this radio is sold under various names like HobbyKing, iMax etc..). The only downside of this radio system is that it, as far as I know, hasn't got any kind of frequency agility. I.e. if you hit noise on the channel you're flying on you're going down just like with the MHz systems. But still, as far as you're not flying it on your 12 foot scale you ought to be fine.

As for features of this radio: it has almost all the features of a basic 200$ Futaba including manual mixes etc. but they can be done only via computer which you have by the field anyways since you're flying your ArduPilot, right? :)


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