Review

Futaba 3GR Radio Control System

By Paul Williams.
Article posted 12th March 2008.

Having decided in early 2007 to return to FE boats after a ten year absence, I had to re-buy all the kit I'd sold or given away when I stopped racing in 1997. One of the first priorities on my shopping list was a high quality radio system. Some research on the net led me to Futaba's then newly released 40MHz synthesised 3GR system. "Synthesised" means the 3GR does not use crystals to set the channel. Instead, the desired channel number is selected from a menu on the computer transmitter and on two miniature rotary dials on the receiver.

Futaba 3GR Radio Set.

I chose the 3GR for a number of reasons. Firstly, for a synthesised computer radio it's relatively inexpensive. Secondly, it has white buttons. And thirdly, it has HRS. HRS is a transmission mode you can select on the transmitter if you are running the radio system in the boat at six volts and you have a digital servo, like Hitec's HS5245. So, what, exactly, is HRS?

HRS is a proprietary Futaba system, so Futaba's web site has a really comprehensive page all about the wonders of HRS, right? Wrong. Not only does the Futaba site not have any tech info at all about HRS, not all of the pages agree about what "HRS" stands for. On one page it's apparently "High Response Speed", another has it as "High Response System". Whatever. Anyway, from what I can glean from various articles and forum posts on the net, HRS is essentially a high bandwidth modulation mode that allows transmitter and receiver to communicate much faster. More data can be sent down the link between rx and tx, at a faster rate.

Futaba 3GR
LCD display and menu controls.

Another reason I chose a regular 40MHz system in preference to a 2.4GHz system was that I knew it would work. When I was looking at radios, there was an awful lot of anecdotal evidence to suggest that 2.4GHz had some serious bugs that needed ironing out. Not wishing to pay good money to be a crash test dummy, I stuck with the tried and trusted 40MHz system.

What's In The Box

So, what do you get in the box? A couple of polystyrene mouldings hold a 3GR transmitter, an R303FHS receiver, a battery holder for four AA cells, a switch harness and a rather thick manual. There are no servos, which can be looked at two ways. Standard servos are pretty useless to me, as they're either too big or not sufficiently powerful for a serious FE boat, so I'm not buying something I'll never use. Or, you could take the uncharitable view that Futaba are maximising profit by not adding some servos that cost bugger all. Your call.

Ownership of the 3GR did not get off to the best of starts. The original receiver in the kit was dead, and it took several weeks to get a replacement. Together with the problems I've had with the 3GR's sister 2.4GHz set, and considering Futaba has, in the UK, traditionally been marketed and priced as a premium product, one has to wonder if quality is all it could be at Futaba.

I briefly flicked through the manual then had to go and lie down in a darkened room for a while. Being a humble FE boater whose radio requirements are left and right, go and stop and the "Today" programme, the manual was full of references to ABS, EPA, TCP/IP and other stuff equally confusing to a dense FE boater. Suffice it to say, most of what the 3GR is capable of you won't use in a boat.

Futaba 3GR

If you get a bit ambitious at some point and want to add a third radio controlled function to a model - say, for example, a wing or set of trim tabs that you want to be able to alter on the go - then the 3GR has a third channel, controlled as standard by a two position switch. I don't doubt this could be replaced by a rotary "pot" to allow a range of positions instead.

Functions you will be interested in from a boat point of view include:

End point adjustment (EPA)
Fail safe
Digital trims
Exponential steering
10 model memory
Subtrim
Timer

To access some of the more advanced features, you must hold down a button as you turn on the transmitter. This takes you to a master setup menu where you can change the channel and the modulation mode (PPM or HRS). Other features like end point adjustment and channel reversing are accessed by pressing the same button after you've turned on the transmitter.

One feature you may find useful is "subtrim". The manual says "Subtrim shifts the entire servo travel range in the set direction". So, if you've used up all the steering or throttle trim, you can effectively re-program the servo neutral point. While this is a very neat feature, one could argue that you should build the steering linkage correctly in the first place, not rely on a clever radio set to correct a gross error.

Futaba 3GR
R303FHS receiver. The two miniature dials allow you to select the desired channel.

Another function that some modellers may find useful is channel mixing. Mixing allows you to slave one channel to another. For example, suppose you build a scale outboard tunnel hull. Mixing can be used to alter the angle of the outboard depending on the throttle position. So, with the throttle wide open, the outboard is trimmed out. As you close the throttle, the outboard is trimmed in, dropping the nose for a turn.

One last feature worth mentioning is "Fail Safe". Fail safe can be programmed to move each of the three channels to pre-determined positions if the receiver loses the signal from the transmitter, for example shutting the throttle and moving the rudder to the centre position. If you build a very fast boat with a water brake (Bluebird K7...now there's a thought...) fail safe could be set to deploy the brake if the signal is lost. Fail safe is only available in HRS mode.

Ok, enough talking. How does the 3GR perform? So far, faultlessly. Yes, the menu system takes some getting used to and you will spend an initial period of ownership constantly referring to the manual, but this is true of any non-trivial item of technology. I will update this article when the 3GR has undergone the true acid test, namely surviving a day racing with SWAMBC.

Verdict

Inexpensive and with an impressive feature set, Futaba's 3GR set should be on your shortlist if you're looking for a new radio.

I bought my 3GR set from Totem Hobbies.

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Last modified: 08th July 2010 @ 09:05