I was searching the market for a nice computer radio system for my new T-Rex 450SA helicopter. I wanted the best radio I could afford, since I would be using it for many years to come. Soon enough, I stumbled across a new technology in radio systems - 2.4ghz. Standard computer radios use 75mhz. 75mhz requires special crystals to communicate between the transmitter and receiver. However, if two people are using the same frequency of crystal on their radio systems, their radios will interfere with each other, causing a nasty crash. I wanted to avoid these troubles by getting a radio with the latest technology, 2.4ghz. It doesn't use crystals to communicate between the radio and the receiver, it switches between many channels every second, which basically eliminates the chance of interference.
Currently, Spektrum is the leading manufacturer of 2.4ghz radio systems. Spektrum is a branch off of JR radios, which offers standard 75mhz radios. Spektrum offers five different 2.4ghz radio systems. Two of them are for land use, and three are for air use. Since I was flying a helicopter, I would need an air radio that they offer (DX6, DX6i, and DX7). I chose to get their best radio, the DX7.
The DX7 costed me about $330 from Hobby Hangar. It includes the radio and receiver itself, plus three S75 servos. I liked this package deal because I could use the three S75 servos in my helicopter. The DX7 also comes with a rechargeable transmitter battery and charger, so that I wouldn't be burning up AA's every time I try to use it. I've been using the DX7 for several months now, and the battery only needs to be charged overnight about every two weeks.
Features - the DX7 has them all! One of the most noteworthy features is eCCPM (Cylic Collective Pitch Mixing). This feature enables you do set up and fly todays most advanced 3d collective pitch helicopters, like the Align T-Rex 450 (Also here on sharedreviews). The eCCPM function automatically mixes the three swashplate servos on your helicopter. Also Spektrum has included not only the standard 3-servo 120 degree eCCPM, but other swashplate designs like 3 servo 90 degree, and many others.
The DX7 has 7 channels (And the DX6 has 6 channels, you get the pattern.). This means that it can control 7 different outputs. The T-Rex 450 that I use the DX7 with only requires 6 channels to fly, but I decided to get the DX7 anyways because of its ease of use and ability to expand later on.
Here are just some features that the DX7 comes with, there are so many that I won't bother explaining them on, but you can find more info online if you really want to: Digital trims, airplane, helicopter, or sailplane mode, sub trim, throttle hold, throttle curve, pitch curve, three flight modes, revo mixing, 3 custom mixes on helicopters, 6 custom mixes on planes and sailplanes, timer, dual rates, and servo reversing.
Now for the field tests - actually using the DX7! First when you try to use the DX7, you will have to program it, so that it has the proper settings for your model. The manual included is very good at explaining the basics, but since each model is different, the manual can't explain exactly what settings to put things at. Hopefully the model you purchased will include information about specific settings that you will have to set. Programming is fairly easy as long as you know what settings to use. The DX7 only has 6 buttons, which is a lot simpler to use than other radios that can have more than 10 different buttons!
After programming my radio for my T-Rex 450 helicopter, I went out flying. Perfect! No glitches at all (Thanks to 2.4ghz!), and plenty of switches so that changing something mid-flight is a breeze. But one thing I noticed immediately is that the spring tensions on the gimbals were fairly weak in my opinion. I opened up the back of the radio, and adjusted a setscrew for maximum spring tension. After that, the gimbals were nice and strong.
Its been several months since I bought this DX7, and I have been loving every minute of it! The new 2.4ghz technology is simply amazing, you wont have to worry about interference at all. Recently at my flying field, someone crashed their $1000 helicopter just due to a small radio glitch! I find myself to be very comfortable flying with my DX7, as I know there wont be any glitches or range issues. If you want to get a top of the line radio system, look no farther than the DX7!