Join Date: Jun 2006
Location: Gold Coast, Australia
Radio Transmitters – Suggestions
How to select a Radio Transmitter
Unlike some other things in r/c car racing, while you may “get what you pay for”, with radio transmitters you can easily end up paying a lot of money for features you neither need or will use. My advice is to consider the features offered by each radio, and see how many of them you need, before making any kind of choice. This is especially important if you’re on a limited budget.
The very first question in selecting a radio is “stick or wheel”. This is probably a no-brainer, and you’ll go with whatever you’ve grown up using. That doesn’t mean it’s the best choice though – some European racers feel that the “stick” type radio is capable of giving you better control of braking functions. Even if it does though, if you’ve grown up using a wheel-type radio, you’re probably not going to switch even if the other type is “better”.
If you’re looking for a new radio, there are lots of things that I think you should not do. For example, if you go to a major race, and find that most of the top racers are all using a brand-x radio, this does NOT necessarily imply that brand-x is the “best” radio. What it usually means, is that the manufacturer of brand-x sponsors these racers, which is why they’re using it. In no way does this mean that brand-x isn’t such a good radio, as if it didn’t work well, the better racers would use something else. All it means is that brand-x is probably one of many perfectly adequate radios, all of which can do a very good job. Unless you’re also being sponsored by the manufacturer of brand-x, keep an open mind. Something else not to do, is to select a radio based completely on what you see and read in magazines. Everyone’s hands are sized differently, and rather than being a matter of adapting your hands to a new radio, you should be finding a radio that matches your hands.
The first step in selecting a new radio, is to pick several up, and see how they feel in YOUR hands. Is it too big, or too small, or too heavy? Does it feel balanced? Try to be objective here. If you’re buying a radio transmitter for gas racing in particular, the races can be up to an hour long, and you want something that fits your hands nicely. Be sure to check how much clearance there is around your “throttle finger”. If there’s a lot of wasted space, you’re not going to have the fine feel you need between throttle and braking. Some radios are adjustable here, so you can adapt them to fit your finger. Check how your hand wraps around the radio handle. Is the handle too big or small? You can always use the type of tape they use for tennis rackets to make a too-small handle larger, but if the handle is too big around for your hands, that’s not fixable.
If you’re right handed, you’re going to have a long list of choices. The list gets shorter if you’re left handed, but there are still lots of radios to choose from. Most radios for left hand use are simply right-hand radios, which you take apart and assemble in a different orientation. This might be a lot of work, but you’ll only need to do it once. Of course, this makes it a bit harder for left hand people to “try out” radios in their hands before buying one.
AM, FM, DSS
Some general notes are that there are a few things you can do to minimize glitching and other random radio interference. Most racers feel that it’s “better” to have FM rather than AM. FM radios may cost a bit more, but it’s probably a good choice to make. As to frequency, you have a choice of 27-band (with six frequencies) or 75-band (with 30). It’s your choice, but it’s more likely if you go for 75-band that you’ll find the frequency clip available when you want it. There’s also the new DSS systems becoming available, which are probably going to eventually replace all the older systems. DSS has a lot to offer, and automatically provides the desirable fail-safe functions too. I think this is the way of the future, and if you can get it for the radio you want to use, I think that would be an excellent choice.
Something to consider if you go with a conventional FM radio on a particular frequency band. At some point, you’re going to have to change crystals because of a frequency conflict. Most racers will simply plug in a different set of crystals and be done with it. However, if you want the very best performance, and can afford the cost, it’s probably to get one or two different sets of modules, so you have a matching module for each crystal. This is a small point, but since the modules are tuned to a specific frequency, it’s best to keep these as matched pairs, and to switch modules when necessary. If you find the additional cost to be excessive though, remember that “most” racers just change crystals, and this almost always works just fine. Still, if you’re after the best performance, it’s something to remember. Try to use matching crystals and modules, and try not to ever use very un-matched pairs, such as a module for channel-90 and a crystal for channel 62.
Regarding cost, while a “more expensive” radio may or may not have “better” components than a less expensive radio, getting a top-of-the-line radio does mean the manufacturer has used the best technology they have available. This too is something to consider. Spending extra money for the best hardware seems to me to be a good argument for getting the more expensive radio models. Try to find out if the reason for the higher cost is hardware or software.
If you’re working with a limited budget, you need to consider the radio’s features, which nowadays mostly means software features. While computer software can do just about anything, that doesn’t mean that all these new-fangled programs are going to do anything useful for you. My advice is to consider the following scenario. You might show up at a major race, and find that your radio is broken, and you have to borrow one from another racer. Let’s say you get to borrow a very basic radio with no software functions at all. If you’ve been relying on your high-tech super radio to do your thinking for you, you’re going to be stuck. That’s my next piece of advice… learn how to all these fancy things with your FINGERS, rather than with software. Forget all the software completely. This means electronic ALS (anti-lock-brakes), exponential, variable servo speed, and all the rest are out. The only things you really need your radio to do, are to match the throttle settings to your car’s carb or ESC, and to match the steering to the car’s steering. Everything else is an optional extra, like buying a fancy set of wheels for your full-size car. If you learn how to control your car perfectly with your FINGERS, and not with trick software, you’ll be a better racer. (Of course, if your budget is not limited, all these fancy software programs don’t hurt anything… they might even be fun to practice with.)
My one exception to the above, is what I would call a “safety” feature. A function like “fail safe” is well worth having. If someone turns on another radio on your frequency, or if your battery pack starts to die out, having fail-safe can mean the difference between your car safely coasting to a halt, or driving full speed into the boards, destroying itself. For that reason alone, I’d move the “fail safe” feature into my own list of highly desirable functions to get. Even fail-safe isn’t going to always protect you from runaways though. For example, if your car’s receiver pack falls out, or the wire becomes disconnected, or the on/off switch fails, there is zero power available to close the throttle… meaning if this happens when your car is going full speed, it will continue that way into the nearest board. The best answer here is a “throttle return spring”, but that’s a different story. The very best answer is to have both fail-safe, AND a throttle return spring. (Note: I’ve been told that a throttle return spring doesn’t work with certain servos, as these servos are too difficult to turn when the power is disconnected. My answer here is to use a servo that DOES work with a throttle return spring, and ignore any servos that are incompatible with throttle return springs.)
Another software choice that can be quite handy is the radio’s ability to store multiple settings. If you race several cars, this means that you can have a setting pre-stored in your radio for each car, so you don’t have to set things up all over again each time you change to a different car. Still, this is just a matter of convenience. It might save you a lot of time, but the results will be the same as setting up the radio each time for whatever car you’ll be racing. I should add that if your radio does have lots of storable settings, and you also have a computer set up with a “driving game”, you can use one of the settings to work with the devices that allow you to control your computer car with the same radio you use to control your r/c car. This is a great way to get even more “stick time. Multiple settings is a nice convenience feature.
Some other things to consider are traveling. Some radios are huge and bulky, and take up a lot of room in your suitcase (or your radio travel case). Others are quite compact. If you like to “travel light” this might be something to consider. It’s also nice if the antenna can completely retract into the radio, so the antenna can’t be damaged in transit.
Another thing to consider is how easy/difficult the menus are to work with. If it’s a computer radio, and you find that you need to change a setting, hopefully you can make the change rather quickly, without needing to get out the manual and figure out what to do and how.
While a radio only “needs” the basic settings, there are a few things you can do to make the radio more suited to your driving style. Most radios have a control for “dual rate” which typically sets how far your car’s wheels turn, when you turn the steering wheel. You may or may not need this function. Some radios provide a similar control that sets the maximum amount of braking. If you find that over the course of a long race, your car’s braking diminishes and you have to pull into the pits so your mechanic can screw in the adjustment so you have more braking, doing this electronically is real handy.
Another function that’s handy (although not essential) is a built-in timer. As you become a better racer, you’ll find that your lap times become more and more consistent. Ideally, you’d have a person with a stop watch timing your laps, and helping you find out which car setting and track line gives you the lowest lap times, but sometimes you just don’t have that option. A timer can help you do this on your own. Let’s say you are out practicing, turning 15-second lap times. Let’s say you set the radio’s timer to 15 seconds, and it goes BEEP every time you reach a certain turn. If the timer is set to the same setting as your lap times, it will go BEEP with your car on the same spot on the track, lap after lap. Now, let’s say you try a different line on a certain turn, and it improves your lap times by half a second. Your timer is still set to 15-second lap times, but you’re now turning 14.5 second laps. What will happen, is that every time the timer goes BEEP, you’ll now be a bit further down track, away from the spot where the timer used to go off. This is the beauty of this system. If someone times you, and tells you you’re turning an average of 14.5 second laps, you can now set the timer to 14.5 and once again the BEEP will go off with your car more or less in the same track position. Any change you can make in your car or track-line to get the BEEP to be further down the track, means you have made an improvement. However, if the BEEP goes off before the car even reaches the same place on the track, you’ve made things worse, not better. That’s how this function can help you improve your racing! (Truthfully though, a small box with a timer, and a small earphone that BEEPS as described above, will do the same thing.)
Whatever radio you’ve got, take good care of it. Don’t walk around carrying it by the antenna or steering wheel, don’t drop it, and when you travel, make sure it’s well protected. If the batteries inside are NiCad, discharge them fully every so often before re-charging, so they maintain their full capacity.
• Once you’ve got your new radio, try to do something to it to make it unique. This is to prevent another racer from accidentally picking up your radio from radio impound, thinking it’s his own.
• If you’re serious about r/c car racing, it might be a good idea to pick up an extra battery pack for your new radio. That way you can always have a pack fully charged.
• If you plan to use the radio with rechargeable cells, it’s always preferable to pick up a battery pack all wired together, rather than to have to use separate cells. This minimizes the chances of your having a problem because two cells aren’t making good contact with each other.
• If you’re storing your radio for a long time, it’s best to remove the batteries before putting it away in storage. This is to minimize the chances of damaging your radio if one of the cells leaks.
• Either mark the radio with your name and phone number, or tape the information to a good place inside the radio. If you ever leave the radio behind when you head home after a race, at least there’s a chance this way that someone who finds it will be able to contact you.
• If your radio has a “fail safe” option, learn how to set it up, then test it. On a gas car, with the engine not running, give the car full throttle and turn the wheels all the way one way, then turn the radio off. The throttle should return to a fully-closed position, and the wheels should return to a straight-ahead position. If these things don’t happen, your settings are not correct.
• Pay attention to how you mount the receiver in your car. For use in gas cars, it should mounted in a way that engine vibration doesn’t adversely effect it, and protected from accidentally being flooded with fuel from an over-enthusiastic pit person. Put tape around it, or use shrink tubing to prevent the crystal from falling out in a crash.