Let's gore an RF-ox!

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Q. I'm curious what receivers and other electrical components you use, and maybe how you linked them together. In other words, what you find works well with your servos.

Radio system selection falls under that category of subjects, which are generally unsuitable for polite company. Think politics and religion when the family gets together for Thanksgiving. However, because of involvement with the control-loop side of the radio system, I quite often get asked about the RF-side of the business. The latter is what the question above is really about.

First, let's back up because what we think of as a radio control system for models can be broken down into several sub-systems. Servos are part of the control-loop sub-system. The transmitter and receiver are part of the radio frequency (RF) sub-system. And both of these sub-system have a power sub-system. E.g. there's a battery for operating the transmitter, and another battery within the model.

Anyway, and let me be clear, we have nothing whatsoever to do with the RF side of things. Also, while I don't mind sharing what 'I' have found over time to be best practice, please bear in mind, I don't have a dog in the hunt because I don't have any involvement in RF system design, or production. Our expertise is strictly with the control loop, e.g. servos.

The point being, while I don't mind sharing my thoughts, because I'm bound to gore somebody's ox when I share what is nothing but my personal opinion, the internet-experts are going to cut loose on me for daring to say a lot of what I have to say. Anyway, here goes . . . just remember, crazy uncles are everywhere!

Back in the day, we had a transmitter, a receiver, four servos, a battery, and a switch. The paranoid amongst us didn't use a switch because this meant one less component to fail. Frequency-wise the RF-link (transmitter/receiver) was initially on 27Mhz but because these frequencies were shared with CB radios (truckers), they were subject to interference (think crashes). This led the powers that be in modeling (AMA) to obtain more VHF frequencies on 72MHz, instead. And life was good.

The latter (72MHz) were ordained to be used for model airplanes and the former (27MHz) for model cars. Eventually cars got frequencies on 75MHz. You may hear of the 6-meter band (53MHz), but these were(are) reserved for HAM operators.

Since lower frequencies are better suited to long distance control, the powers that be were talked out of the exclusive use of VHF frequencies and sold a bill of goods involving UHF frequencies (2.4GHz). However, now we're getting into politics, so I will leave things there. Suffice it to say, modern model airplane RF systems operate on 2.4GHz (and some have 900GHz for telemetry, but I digress).

Meanwhile, the battery sub-system for the transmitter output 9.6V via an 8-stick pack (eight 1.2V nominal AA-size NiCd cells in series). The receiver sub-system operated on 4.8V (four 1.2V nominal AA-size NiCd cells in series). With changes in chemistry, transmitters these days may be on anything from 7.4-11.1V (usually with LiIon packs). Receivers and servos once operated on 4.8V then as much as 6.0V and these were(are) referred to as standard voltage. High voltage generally being considered 6.6-8.4V nominal.

On the control-side of things, servos which were analog with a refresh rate was 50Hz from the receiver gave way to digital schemes. Refresh rates increased, also and today, 330Hz is relatively common. These days, SV (standard voltage) is going the way of the Dodo, and HV is become the norm. As relative newcomers to the servo-business (2013), we decided early on to forgo SV servos and 100% of ours are HV (actually, a new terms has come into being; WV for wide-voltage, which our servos are also because they'll operate on anything from 4.8V to 8.4V).

Speaking of back in the day; RF-manufacturers tried to lock modelers into their orbit (they still do). One technique was to make minor changes in the 0.10" pin plugs that interconnected the components. Futaba, for example, used a plastic plug with a small blade sticking up. Hitec used another method, and JR yet another. None were compatible, of course.

This was all about controlling the modeler, e.g. keeping him from buying servos and such from competitors (they wanted you within their own ecosystem so they could charge whatever they wanted because it's always about the money). Modelers being rebellious sorts by nature, well they rebelled, which led to the adoption of the universal connector. And life was better.

Not willing to give up, the RF-manufacturers latched onto other schemes to bind you to their skirts. For example, they adopted serial-buses for the control loop. However, most modelers (now wise to the RF-manufacturer's games, e.g. wary of being penned up again), saw through this. Thus, the RF-guys were forced to ensure ordinary servos interoperate with their serial-bus schemes. Life continues!

Of course, this didn't stop the gullible from buying into the whole serial bus architecture thing, but by and large, most modelers dodged that bullet - whew! Meanwhile, technology being what it is, has changed. So the RF-guys soon abandoned one serial bus scheme for another. This is why you may see reference to S.Bus and S.Bus2 (and presumably S.Bus3 will make an appearance, eventually). And that's just from Futaba because JR (another popular RF-system manufacturer) had their own serial-scheme for communicating with servos (and of course, it was totally different, e.g. incompatible with Futaba's transmission scheme). And guess what? Everybody else in the RF-business tries to lock you in with their own incompatible scheme. This means once you pick, let's say Spektrum, then you're locked into buying their receivers. Ditto, Futaba, Hitec, JR, Graupner, et al. . . . ARGH! However, there are some companies that specialize in making clone receivers. The bi guys bad mouth them but in my experience, they work just fine. Me? I've been using FrSky Futaba-compatible receivers for years. And the world hasn't come to an end because they work just fine for me. Even with really expensive models!

Why do RF-manufacturers do this? Simple, follow the money - or - haven't you wondered why it is a significantly less capable servo (e.g. one not built as well, or as powerful as is available from ProModeler) costs $229.99 while ours is just $100. Answer? It's because theirs carries the RF-manufacture's label (meaning they can charge more for it). Of course, you can't convince a lot of people of this fact because as Ron White (comedian) loves to point out . . . you can't fix stupid. But again, I digress.

And there are other tricks being used to play up the gullibility of modelers. For example, a favorite is to involve the marketing department and play games with product names. Ones implying safety are popular. Again, this is mostly to try and bind customers to an RF-manufacturer's skirts, but sometimes it's to do with inferior transmission technologies (Google 'brownout' with respect to various popular RF-manufacturers). This will be instructive on why dual battery systems are on offer, and it having nothing whatsoever to do with batteries not being reliable.

Other tricks RF-guys use try t play up the use of two frequencies without mention of the fact one is for RF and the other - technically also for RF - is for telemetry instead of control. Meanwhile, technology inexorably marches forward and this is why, with Spektrum for example, you have DMS, DMSS, DMS2, DMX, (and presumably something else coming soon, perhaps DSMX2, slated to make an appearance). And the thing is, each of these schemes obsoletes the previous one so the modeler, bless his heart (wallet) is stuck on a treadmill. Hmmm . . . follow the Benjamins became a saying for a reason.

Oh, and the RF-guys love switching these schemes up because they have learned a neat trick. Basically, you don't skin the sheep, you shear him, instead. And you can do it over and over and over again with the help of marketing because folks are (for whatever reason) brand loyal. You know, like how there are Chevy guys just like there are Ford guys. It's human nature to pick a team! But this all boils down to money, or more to the point, separating you from 'your' money as expeditiously as possible!

Me? I don't play the game. And I keep things simple. While I see guys who fly systems where you need to add more and more receivers (satellites) to ensure a 'robust' signal, I have been well served by a more simple system. Specifically (and bear in mind, I don't sell any RF-system so I don't have anything to gain or loose by sharing my opinion because all the RF-manufacturer's hate my guts for stealing 'their' servo-customers), well, I still fly a Futaba system. And an old one at that.

More to the point, my Futaba system is 15 years old . . . but as long as it works, I'll keep using it. Earlier I referenced simple. By this I mean my Futaba system is simple because it consists of just one diversity receiver (and I've seen models loaded with as many as four diversity receivers). By diversity I just mean it has two little antennas sticking out of it.

So will I ever change? Maybe. Honestly, I don't know. Spektrum is real good about advancing the sport. For example, they have the AS3X system, which adds gyroscopes within the receivers. Gyros are good because they make me look like a better pilot - pretty neat. But they're also the guys who promote using a butt-load of receivers in some models, which confuses me. For example, I have a problem with this because nobody has explained to my satisfaction why some models are fine with just a receiver, but others need me to add a satellite, or two, or four satellites. Four? Yup! Fortunately you can add gyros to any radio system.

Then there is Jeti. They have an interesting system, but so does Graupner. As does Hitec (and JR is trying to make a comeback). Unfortunately, these are ALL mutually incompatible - grrrr. So who knows? I may end up trying one of those inexpensive systems from FrSky - I dunno, I may buy Futaba once again. Ask me again in a few years.

Finally, let's boil it down to what you're asking. For my purposes (models as large as 126" with a 200cc engine, I use one receiver, one battery, and two switches plus our servos (actually, I use two receivers in that model, but one is handling the servos in the tail group and the other handles the ones in the wing plus throttle - both controlled by the same transmitter). That's the exception - and - I eschew the use of 'box' systems as needless complication.

But it doesn't matter because sometimes modelers just like to complicate their lives. Thus, box systems are very popular with some, especially the giant scale and jet crowd. Hence, my opinion regarding this subject (that box systems are an unnecessary complication) is about as welcome as farting in church. Anyway, let me don my flame suit because the hate mail is about to start!

Note, my philosophy of keeping things simple works for any brand of servos so I'm not just talking my book. As for why I use two switches, it's because switches fail. And also because using two lets me feed the receiver twice as much current (the connector is limited to 5A so using two means I can give the receiver 10A of current for the servos).

This last has become important due to powerful servos - where just one can demand as much as 5A. And by the way, I've been down the road of snake oil switches that supposedly fail in the on-position and been burned (read crashed a model because the magic let me down). So I stick to simple mechanical switches. Note; the ones we offer on our website are overkill because they're rated at 20A while the connector is rated to 5A. Most HD switches are 10A but I like overkill with my switch because it'll last longer.

And like I said, I prefer Futaba - but - this may change. Ask me again when my trusty Futaba transmitter dies (inevitable). Does this answer your question? Or have I made things clear as mud, instead? I'm sure I've gored plenty of oxen with my response because I have zero brand loyalty to any of the RF-manufacturers and am very wary of being roped in. Think of me as not having religion about RF-brands, and they hate me for it. Is what it is. However, if there is such a thing as 'the' Cardinal rule? Yes . . . keep it simple!

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