I am new to RC. After hours on a flight sim, I think I am ready to invest in my first radio system and a .40 size electric trainer aircraft. After some research, I think I am pretty well set on a 2.4 GHz radio. Futaba has just come out with their 6EX, a designed 2.4 system. The alternative is the Spektrum DX-7. I would appreciate input on the differences between them and the pros and cons of each - anything to help me make an informed buying decision. TIA.
I don't own either one but have talked to several guys that do. The main complaint against the Spectrum is that it has two receivers linked together by a cable and they must be orientated approx. 90° from each other. Not a problem in a large airplane but can be in a small fuselage. The Futaba has one receiver with two antennas on it which is much easier to install.
If I understood them correctly there is a difference in how they operate. The Spectrum uses two channels out of 41 or so and picks the best of two signals. The Futaba sequences through the channels and rejects anything that isn't right and moves on. To me, this fits the definition of spread spectrum in that the signal is spread over all of the band.
My vote (for what it's worth) is for the Futaba. But, I am mostly into sailplanes now days and the fuselage is usually pretty cramped in the ones I have, and plan to have.
if the plane is so small as to limit RX size, it's more than likely a park flier or thereabouts and spektrum's AR6100 RX units do the business w/o the 2-part setup.
It won't make a difference to the way it's transmitted but they will have experience of tx programming and they will probably have a brand preference that will make using a buddy cord easier. If they all fly futaba buy futaba, if they all fly JR buy the spectrum.
| See what your local club flies. | | It won't make a difference to the way it's transmitted but they will | have experience of tx programming and they will probably have a brand | preference that will make using a buddy cord easier. If they all fly | futaba buy futaba, if they all fly JR buy the spectrum.
That's probably the best answer.
Don't worry too much about the specifics of how the radios actually work, as they generally do the same thing and both do it well. Both have good range and are known to work well.
Sure, the DX7 RX has two parts but they're quite small. In a 0.40 sized plane you'll probably have no trouble whatsoever.
The biggest difference is probably in the computer radio part. The DX7 has a fairly full featured computer radio and gives you seven channels, where the 6EX has a relatively basic computer radio and only gives you six channels.
Six channels is generally enough, but you'll want seven if you fly something like a full house sailplane (with four servos in the wing) or something like an Ultra Stick set up the same way.
On the other hand, the 6EX FAAST is cheaper, even if you go ahead and get the package with digital servos to match the digital servos that the DX7 comes with.
You'll probably want to do a buddy box. While you can get cords to connect a JR (Spektrum uses JR radios) to Futaba, it adds a layer of complexity -- and while the instructor at the club may have a buddy box and a cable, the odds are good that he doesn't have a JRFutaba cable.
One thing I can say with relative certainty -- you're doing the right thing looking at spread spectrum 2.4 GHz gear. You can still buy 72 MHz gear, and it's cheaper -- but it just doesn't make sense anymore to buy it new. Buying it used is OK -- lots of people are selling it, so it's cheap -- but buying new 72 MHz transmitters is just throwing money away unless they're high end ones that can take 2.4 GHz modules.
Well, I'm also reasonably new, and have the DX-7, while my buddy has the Futaba 6EX. Both of us are flying Telemasters with electric power. Both radios work really well, and the two piece transmitter on the DX-7 is really a non-issue in a .40 size plane. The 6EX is a "2.4ized" standard 6 channel Futaba, the DX-7 is basically the same as a JR 7102 (I think that's the number). The JR fans prefer the Spektrum, the Futaba fans like the 6EX, but the experienced Futaba guys at our field are waiting for the 2.4 versions of the 7C and 9C before they consider replacing anything.
I picked the DX-7 because:
- I found the programming more intuitive than the 6EX, but that's really personal opinion
- Individual timers for each model memory (6EX doesn't have a timer). This way if one plane has enough juice for 5 minutes, and the other
10, I don't have to remember (as long as I start the timer)
- The receiver is bound to a specific model memory, so you can't accidentally fly one model with the settings for another (for example, a reversed channel).
- Personally, I think it will be "enough" radio for me for a long time, whereas I could see growing out of the 6EX and wanting to move up in a couple years.
At the end of the day, once the plane is set up and you're flying it, either radio is great for a beginner. In the short time I've been at this, neither 2.4 radio has had a glitch, even flying the Telemasters (6 foot wing) to "can't quite see what it's doing" altitude. There has been at least one plane almost "shot down" when someone inadvertently powered up their radio in the pits on the same channel, and we have a small club.
Get the Futaba. They waited a while after JR introduced the SPEKTRUM and then improved on the technology before introducing their new 6ES FASST system.
I have the Futaba 6EX. Works fine. I bought it because I intended to convert some airplanes that already had servos in them. The 6EX Xmitter is a very entry level computer radio. It has all DRs and Expos on one switch. Looks cheap, made in China. My real concern is the receiver. Looks like it won't be compatible with the module systems in the higher level Futaba Xmitters. So it's a dead end.
I'm looking at the modular systems offered by XPS now. You might want to take a look.
My experience with the 2.4ghz radios has been poor in the sense that it cost me a brand new model. I built one of the Super Airliners with a 2.4 gig radio system. First flight the model apparently got a bit too close to a cell phone tower, both motors cut out and all of the servos flipped out either one way or the other to full deflection. The debris crater was about 5 feet in diameter with a thump that would have made youtube proud. Thankfully, both lipo's, both motors, and all but one servo survived the uncontrolled descent.
Aside from rarely being hit with minor glitches, my 72 mhz futaba has never let me down like that. Cell phones and microwave ovens all operate on or near the 2.4 ghz band. It seems foolish to me to trust a model to a band that is already well saturated with unrelated traffic.
We have found just the opposite to be true. Here in North-Central Florida we have a Club 40 Pylon Racing circuit that has races in five cities, metro and rural. We usually have anywhere from 24 to 37 racers show up to race. As of this date, we have 10 racers on 2.4 GHz. We have had as many as three of them racing together in one heat. They have performed flawlessly in this race environment.
Cheers -- Lyman
"On so-called global warming or climate change, let us not scare ourselves with catastrophic forecasts, or use them to defend and promote irrational interventions in human lives."
I don't know about the cell phones in the states, but the ones up here in Canada run in either the 800-900 MHz range or 1900-2000 MHz range. So even in the top end that would be a 400MHz difference between what a cell phone tower and a 2.4GHz Spread Spectrum radio runs at. That seems like quite the spread since 72MHz air radios and 27MHz ground radios are a lot closer than that.
I am not saying that the Cell tower was not the cause of the crash, but it seems awfully odd to me.
It sounds EXACTLY like BEC shutdown o me. Those 2.4 gg receivers draw more power than we are used to, and on a marginal setup thats enough to flip the regulators into crowbar mode.
HS55's on 0.5v seem to crawl to their endstops and beyond..
2.4 gig receivers will simply stop sending servo updates if they lose coherent data.
I have to agree with the National Phi.sophiker here. If the receiver had been swamped, the servos would have remained in their last positions and would NOT have been driven to their stops at one extreme or the other.
Besides, cell towers run minuscule amounts of power output - nothing like 100 watts or more.
However, as another poster pointed out (Gavin) any receiver on any band can be swamped by any powerful enough transmitter on any band/frequency if the power output is high enough and the receiver is close enough. Our receivers' filtering systems are more like sieves than brick walls as some would have you believe.
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