Multiplex is a well-established manufacturer of proportional radio gear, and has traditionally been seen as a 'high end' brand. There's no doubting that they've always been at the forefront when new developments have arrived, for example end point adjustment, control input mixing, separate model memories and modular components. Plainly that has to be reflected in price, and the Multiplex R/C of yesteryear was always quite expensive. However, in the early '80s they began offering cut down versions of their radios at a more affordable price. Up until the introduction of the Evo Tx in 2003 the Multiplex series was pretty widely divided between the top and bottom of the range. Incidentally, it was the Evo, if you remember, that introduced the concept of software selectable frequencies. And so we move to the subject of this review, the Cockpit SX, a transmitter that’s aimed squarely at the advanced beginner and the established flyer looking for a competent mid-range radio that won’t break the bank. In practice Multiplex have not only hit the nail on the head with the SX, they've firmly driven it home in one hit! There's little else I can see on the market that offers so much for such a small price. So will it live up to its promise?

Opt for the 'standard' set and you get a 7-channel Tx, a synthesised Rx and one servo. There are 12 model memories available, with up to three flight phases available within each memory for fixed-wing, and four flight phases for helicopters. The Tx has a frequency synthesiser fitted as standard, which is quite remarkable given its 'budget' standing. A comprehensive variety of classic mixing types are available from the easy-to-understand menu system, and three free mixers are possible for every model memory. Two timers are included, one of which will set off an audible alarm if pre-set, and a 1500mAh NiMH battery offers more than six hours of continuous use. Four basic model types are catered for: Easy, Acro, Glider and Heli. Of particular note for glider pilots is the capability of controlling a full-house four-servo wing, allowing proper crow-braking, flaperon and snap-flap. For helicopter users, the conventional Heim-type head plus three- and four-point CCPM versions are covered. Throttle and pitch have five-point curves available to them. The charging socket that's neatly stowed behind a sliding panel on the top edge of the Tx also serves as a buddy box socket (the SX being capable of both 'Master' and 'Pupil') and also as a data connection using the optional USB data cable. This helps future-proof the SX somewhat as operating system upgrades will be available via the internet. Four sets of stick tops are supplied, varying from short and spiky through to long and smooth.

Ergonomically the transmitter works extremely well; it sits very easily in the hands with moulded recesses on the back, in which your fingertips easily rest. For a 'thumb on stick' operator like myself it's quite possible to grip the Tx single-handed and still operate the stick. Both the sides of the Tx and the stick units are angled slightly inwards by about 5°, a departure from the traditional 90° that works exceedingly well, feeling neither odd or wrong. The aerial is pretty long at almost 1.4m (55"), but the Tx isn't particularly unbalanced by this, with just a small tendency to tip down towards the horizontal when held in the hand. Use the neck strap, though, and the Tx hangs perfectly level; a perfect example of the degree of thought that's gone into the design. Those that find the aerial a bit too long for their taste will be glad to know that a high quality 'rubber duck' variant is available, as is a knuckle joint adapter if you wish to set a different angle other than straight ahead.

The switch gear is interesting in that it comes 'fully expanded', which means that it's fully fitted-out as standard. There are two momentary switches (one each side) and three two-way switches that can operate rates, pupil / teacher, snap-flap, direct throttle or switch in a particular mix. A three-way switch provides flight phase control or operation of a mix. Located on the outer edges are two slider channel controls, which cleverly have an operating lever on both the top and bottom sides of the casing, allowing either your thumb on the top side or your forefinger on the bottom side to control them. A small detent allows you to determine the centre for the slider. Trims are digital, of a conventional rocking switch design, and again not located directly across or down from the stick unit but more towards the corner that your thumb would move to naturally when holding the Tx. Stick spring tension is adjustable from within the set, access being via a number of torx-headed screws, for which a torx-headed screwdriver is provided. A very nice feature is that your chosen throttle stick can be adjusted for ratchet, friction, a combination of both, or nothing!

A pretty comprehensive manual is included, printed in separate sections in English, German and French. Manuals can be funny things, often being too simplistic and a bit patronising, or too complicated and difficult to get on with. I suspect the authors are experts in their field and often too knowledgeable to approach the subject from the punter's viewpoint. The SX manual is a very decent effort though, with a mix of text, charts and pictures. Some of the more detailed programming might take a couple of goes to get right, but follow the steps in the manual exactly and you'll always get the right result. Also included amongst the EU paperwork and CE certification (you know, the stuff that says, “don't brush your teeth with a chainsaw”) is a folded A3 page with a full flow-chart of the menu system, and overleaf are all the model types and their respective channel assignments. Easy enough to fold up and stow in the bottom of your Tx box for those 'on field' programming moments.


All programming, adjustment and channel selection is controlled by the '3D digi-adjustor'. Pages and functions are leafed through by rotating the knob, whilst jumping between menus and confirming settings are set by clicking the knob down. A short press does most things, whilst a long press will get you back to the start screen. The digi-adjustor is the first thing you'll use when operating the Tx, as this defines your chosen frequency. When you first switch on, the screen tells you what frequency and channel is currently selected but no RF is transmitted, which is confirmed by a continuously illuminated blue LED. A single press of the digi-adjustor accepts the choice of frequency and allows the RF to be transmitted, with the blue LED changing to a slow flash, accompanied by a short beep melody in confirmation. A throttle safety feature is pre-set (but can be disabled in the software) that requests you to return the throttle to idle before allowing you to continue. Frequency selection is very simply achieved by holding down the digi-adjustor whilst switching on. Release the digi-adjustor and the channel number flashes continuously on the screen; rotate the digi-adjustor to select your new frequency, press the button once more to accept it, switch off and then back on again and you have your new frequency... simple! There have been a few mumblings about the dangers of channels being too easy to change, and the dangers of incorrect frequency selection, but Multiplex' use of a confirmation step involving the digi-adjustor makes this process very safe... possibly safer than manually changing crystals as the channel numbers are large and flashing on the LCD screen during the process! Surely better than poorly printed lettering on the side of the crystal, or a worn / ripped tag attached to its side?

Also available as an optional extra is the 'channel check' module. This plugs into an appropriate slot inside the Tx and will check your chosen frequency when you switch on by listening for any transmissions. If it detects anything on that frequency it gives a read-out of the signal strength and offers you the opportunity of changing to another frequency or overriding and going ahead with your choice. All of this is done with no RF output from the Tx until you decide what to do. I believe this offers the best safety with regard to frequency control of any current system.

The SX will handle up to eight different Tx modes, with the choice being set in the menu and the chosen throttle stick being brought into play and adjusted via the torx screws in the back of the unit.

Setting up a new model is a fairly simple affair. The level of model complexity will govern the Rx you have to purchase, as servo channel assignment isn't possible with the SX and certain channels are needed for certain servo outputs. A simple four-channel Rx will be adequate for most models using a single aileron servo, or more aileron servos using Y-leads. Moving on to a five and seven+ channel Rx opens up the full capabilities of the programming, however. All of the typical abilities of modern computer radios are present, i.e. adjustable travel volume, end point adjustment, dual rates and exponential.

Switches are assignable for the mixers. The SX is likely to be a very useful tool for glider pilots as it will quite happily handle a 'full house' 6-servo set-up, allowing all the fancy mixing including crow braking, snap-flap, camber control, automatic aileron differential suppression under crow braking, coupled aileron and rudder and three separately definable flight phases.

Helicopters are well catered for, with all the main head types being available. Direct throttle control on a slider is there, and also a throttle-cut function. As per the fixed-wing menus there are three flight phases available, plus a fourth phase for autorotation. Again as per fixed-wing, the transition time between flight phases is controllable for slow, medium and fast.

Earlier Multiplex gear centred its servos slightly differently from other makes, the Evo range countering this by having selectable servo 'shift', but the SX moves completely over to the current norm of 1.5 milliseconds. There's nothing intrinsically wrong with either position, but this is good marketing sense on Multiplex' part as users of other brands will have no issues with differing servo centres. I set up a few models for use with the SX, the first being a Shock Flyer-style Depron indoor job. These models are essentially quite simple affairs that use a single aileron servo but gain their abilities through huge control movements. I chose an 'Easy' model template, having already set my choice of mode 2 for the basic Tx layout. Without reference to the manual it was quite possible to set the model up in its basic guise and get it to a flyable state. Servo movements were easily set, as were the enormous amounts of exponential essential to this type of model. My only reference to the manual came when adding a small mix to induce down elevator during knife-edge flight, to correct a small pull towards the canopy. Following the manual was easy, as setting up the free mixers cleverly asks you which stick movement you want to be in which part of the mix. For example, when in the free mixer part of the menu it asks which is the primary control - rudder in this case - so you move the rudder stick until the symbol on the display stops flashing. This is repeated for the secondary control, and a switch to activate and deactivate the mix if you so wish. Once that's done then setting the amount of mixing is just a matter of selecting the percentage via the digi-adjustor. Very easy!

The next model was 45" span electric Extra 300. For this I used an 'Acro' template as it allows flight phase switching. This particular model needs two flight phases, one for conventional aerobatics and another for 3D. The manual allows for this by asking that the model be set up completely in one memory, allowing you to then create one or two more flight phases within that memory that can be adjusted to whatever parameters you wish. Again this was very straightforward. three free mixers are available, and again I applied one for rudder / elevator compensation for knife-edge. Snap-flap and camber control are available in this template, as are snap roll set-ups using the momentary switches.

For electric models a very useful timer function is available (one of two) that can be set to count up or down, from a pre-set value to an alarm via the throttle control. Move up from zero on the throttle stick and the timer starts, pausing when you return to zero. This is very useful for electric gliders, which might spend a considerable portion of flight time gliding in lift with the motor switched off. A second timer that will run concurrently can be assigned to any switch. Affording a basic set-up to a high performance full house glider using the 'Glider' template was simple and straightforward. As expected the SX was perfectly capable of doing everything needed; maybe not with quite the ultimate fine control that high-end radios offer, but given the price bracket this radio falls into it was a very impressive effort, and I think few would be able to complain.

Summing up, what can be said for the Cockpit SX? Ergonomically it's superb, feeling very good in the hands. Build quality is fine, the display screen and switch gear is adequate rather than excellent, but one must remember the price. Software and programming is excellent for this sort of money, the glider functions being strong without detriment to the other types. The jewel in the crown is the 'fitted as standard' synthesized channel selection, which marks a new standard in this price bracket for radio gear and makes the Cockpit SX remarkable value for money. Jumping into probably the most hotly contested part of the market with the Cockpit SX, Multiplex have engineered a very good piece of equipment. I wonder what the other manufacturers must be thinking? I suspect there's a fair bit of hand-wringing going on!