Multiplex mc4000 Review

by Mike Shellim 2004, updated March 2006, April 2006

Introduction

The 4000 is Multiplex's top-of-the-range set and is targeted at modelers with complex models (scale models, F3X gliders, jets etc), who demand ultimate flexibility.

Specifications

PCM or PPM 7, 9, 12
Power supply 6 Nicad cells, 3000 mAH NiMH
Pulse width MPX (1.05-1.6-2.05 ms) or Universal (1.0 - 1.5 - 2.0 ms)
Weight (inc. 1.7 Ah battery) approx. 53 oz.
Dimensions 8.66" x 9.4" x 3.15"
4 line x 20 character LCD

Compatibility

The transmitter supports a number of transmission modes selectable by the user.

PPM 7 and 9 modes are compatible with most 'big brand' PPM receivers, and virtually all third party receivers. PPM 12 mode requires the use of a Multiplex 12 channel receiver.

Multiplex's proprietary PCM mode is also supported, but MPX have stopped producing matching receivers in favour of the PPM / IPD units.

Case and Internals

The transmitter case is almost identical to the 3030. The main changes are a larger LCD, the "4000" logo, and the words "16-bit controller" under the LCD. There is also a second socket for a battery discharge resistor is on the right hand side of the case (more on that later). Sets manufactured since 2005 have a switch under the LCD to operate a backlight.

The inside of the case is dominated by a plug board with 12 sockets labeled A-M (except J, presumably because it could be confused with I). These are for the cables connecting the sticks, sliders and switches, providing the main flight controls.

A further set of 12 sockets is for the 'secondary' switches for controlling flight modes, mixer input switching etc.

The switch assemblies use standard Hitec/JR servo connectors so it will be easy to make up your own.

Scanner (not available for 72 MHz)

An optional scanner unit is available. The most useful feature of the scanner is the automatic Channel Check function. At switch on, the system scans for another Tx on the same frequency and if it finds something, it blocks the Tx from radiating. This is a great safety feature. However, for this to work correctly you must remember to enter your frequency into the Channel menu whenever you change Xtals.

The scanner can also be used in a more conventional way, via a system menu. A histogram of the frequency band can be displayed, showing the signal strength on each channel. A 'memory' feature can record channel usage over the previous 10 minute period. This flexibility is approaching that of a dedicated scanner unit.

The transmitter crystal is accessed by first removing the back of the Tx case, then removing the RF module. A little cumbersome.

Battery

A 1800 mAh 6-cell pack was supplied on my unit. Following a full-charge, duration was 3 hours 45 minutes continuous running with the aerial fully extended. I have since fitted mine with Panasonic 3000 mAh NiMH batteries which are good for around 5-6 hours. I understand that the latest sets are supplied 3000 mAH NiMH batteries.

An alarm sounds when the battery reaches a cutoff voltage. This voltage can be adjusted by the user via a menu. Using default cutoff voltage, I have around 10 minutes in which to land with the 3000 NiMH cells. However this margin needs to be checked as some NiMH cells are notorious for their steep discharge curve, especially as they age.

The battery can also be discharged with the Tx switched off, by the use of a discharge resistor encased in a special DIN plug (supplied with the set). This fits into a socket on the right hand side of the case. The discharge process is activated via a system menu, with automatic termination at a predetermined voltage.

Software Architecture

Instead of the long "feature list" of Far Eastern sets, the 4000 presents you with a small set of building blocks which enable you to tailor very powerful and elegant solutions.

Freely assignable functions and channels

The 4000 allows completely free assignment of flight controls. So any stick or switch can be used to control any function.

Channels numbers are also freely assignable, so you can emulate the numbering of your old R/C system, or you can assign all your functions into the top channels thus allowing the use of a micro receiver. Excellent for indoor flyers.

Flight Modes

Flight modes allow sets of certain parameters (e.g. control travel, aileron differential, dual rate, presets etc. ) to be switched during flight.

Up to five flight modes may be defined on the 4000. Each flight mode is assigned a switch and a priority. If more than one flight mode is active, the highest priority flight mode takes precedence.

Flight modes can be given easily remembered names and the currently active flight mode is displayed on the operating screen.

Flight mode switches are operated by generic 'secondary' switches. This means they can also be used to selectively activate or disable mixer inputs. This is incredibly useful, for example in a typical glider Landing mode you'll normally want to disable snapflap mixing

Trims

Trim levers have their own control codes TA,TB, TC and TD. It's possible to use assign them to functions just as with any other widget.

Virtual Switches

In addition to up to 12 physical switches, the system supports a useful set of "virtual" switches. These provide additional functionality:

Transfer switches - these treat 3-position switches as if each switch position is a discrete on/off switch in its own right.
Momentary switches - click on, click off.
Control switches - on/off based on the position of a proportional control.
Analogue switches - a proportional control attenuates (rather than simply activate/deactivate) a particular feature. This is a unique and very useful feature.
Logical switches - create a switch based on AND / OR rules with other switches.

All physical and virtual switches can be specified equally in most of the programming screens.

Mixers and Curves

Mixers and curves are the heart of the mc4000's programming model. All mixer inputs are transformed using 3,5,7,9 or 13 point curves. By default, 3-point curves are used, the higher resolution curves come in useful when balancing up paired servos or for programming non-linear responses.

Some of the things you can cook up:

Flap-elevator mixing so that flap never deflects more than a set amount
Retractable u/c with sequenced doors operated by multiple servos.

If you find yourself repeating identical non-linear curves for different mixer inputs, you'll can abstract the curves into a multimix which act like black boxes and can be re-used.

For more information on mixers, see Using Mixers

Analogue Switches

Sometimes you want to attenuate (i.e. reduce the 'volume') of one function based on the position of a flight control. On gliders for example, it's often desirable to reduce the amount of aileron differential as spoiler is deployed. Or you may wish to reduce the amount of snapflap mixing as flap is applied.

Analogue switches are a general feature which allow you to do this kind of thing. They are incredibly useful for glider flyers, and seasoned power flyers will also find many uses for this facility.

More about Flight Modes

The program on my Nyx demonstrates the cleverness of the 4000's flight mode implementation.

The flight is flown using a three position switch for - Launch, Normal, and Landing phases
Before the flight, I may want to preselect F3F mode or Aerobatics mode for the 'Normal' flight phase.
In 'F3F mode; I may also want to preselect reflex or unreflexed.

For this, I created five flight modes for: Launch, Landing, Aerobatic, F3F/no-reflex, and F3F/reflex. By assigning them to three switches and setting the relevant priorities, the flight modes can be cascaded from switch to switch exactly as described above.

So far so good. However, in practice, you'll also often want to use the flight mode switches to program interlocks for the spoilers, flaps etc. This easily done with the 4000 without any special hacks. So in the above example, flaps can be disable except in Launch mode, and spoiler disabled except in Landing mode. Snapflap mixing is enabled in the F3F and Aerobatic modes. This is exactly as I would want to fly my F3F model, but if your needs are different, then the 4000 will allow you to tailor your own interlocks. It does not impose its own solution.

With a little more creativity, you can use the flight mode switch to toggle between different servo response curves. So you can have positive and negative snapflap in Aerobatic mode but only positive snapflap in F3F mode.

I should stress that, despite all this flexibility, the whole flight is still performed on a single easily accessible 3-position switch. The usefulness of this cannot be overstated in terms of reducing the load on the pilot.

[Note for 3030 users - flight modes are not as flexible as switching between completely separate model memories I have never found this to be an issue.]

Misc Software Features

A couple of other features which are worth mentioning:

Control and Mixer "Slow": Controls can be "slowed" with different speeds in each direction. In addition individual mixer inputs can be "slowed" with different speeds in each direction. Control and Mixer Slow are additive.
Timers: Five programmable timers are provided. Timer 1 can resolve to 1/100th sec. Others to one second.

Documentation and Support

The 94-page English user manual is based on version 1 of the software, with an additional 15-page loose addendum for v2 of the software.

The manual is a let down. There are several misprints and mis-references, and some of the most powerful features including Servomix and Multimix are barely mentioned. There is no real attempt at showing the philosophy behind the system.

However, there is unofficial user-based support group for the 4000 on the internet - see Contacts. If you are completely new to Multiplex, read also my 3030 Pages, in particular the 3030 Guide.

PC Software

P4000 is an optional software package running under DOS which provides backup, Tx simulation and 3030 conversion facilities. A cable is supplied to connect the PC to the transmitter.

3030 Conversion Program

This is the first thing which existing 3030 users will want to use, but the documentation is sketchy to put it mildly. I also had problems getting it to run program on my main Win 98 PC - it crashed with a run-time error. However it did work on the second PC with no problem.

Since the documentation is a bit lacking, I'll describe the process in more detail here. If you don't own a 3030 you can skip this section.

The first thing is to connect the 3030 Tx to the PC using the supplied cable, then read all the model memories from the 3030 and save them to a file with "D30" extension. Then re-open the file, and select one or more individual models for conversion. Use the space bar to tag each model. The converted data can either be sent directly to the mc4000 or saved to a CIF file which can be used later in the simulation program.

The conversion has a couple of restrictions - it doesn't handle 3030 user mixers, or helicopter mixers, and the built-in mixers are converted to servomix. Be that as it may, I managed to get all those carefully honed settings comfortably into their new home and the conversion for the Ellipse 2V was spot on.

Overall I'd like to see something more usable for English speakers, preferably running under Windows and Mac. I'd also really like be able to do cross- reference reports on the PC. For example a listing of all the functions of each stick, slider and switch. It's too easy to configure a slider to do something obscure only to forget about it later on. The only way to glean this information is by laboriously paging through the programming screens on the Tx.

P4000 Memory Backup Program

The P4000 backup software is very reliable and is now available free. However, it was originally designed to work under the MSDOS operating system and requires a specially modified DOS emulator for to work under more modern Win32 OS's (e.g. Windows XP). See P4000 Dosbox for a free solution.

Tx Simulator

The Tx simulator is provides a complete simulation of the Tx functions on screen, complete with rotating servos. However in spite of its cleverness, I found it tricky to use and of limited application.

Conclusion

Let's get over the caveats first. First, the learning curve will vary from 'steep' to 'extremely steep', depending on your ability to program a computer. The very poor manual doesn't help either although the tutorials on this web site may alleviate this.

The bottom line is, if you don't have any computer programming experience, then the 4000 may not be appropriate unless you have a good understanding of the tutorials on this web site and have somebody to help you.

Neither is the 4000 justifiable for simple applications like trainers, 2-servo wings etc. - it is a heavyweight system for heavyweight applications.

Finally, many pilots will find the size and shape a little unergonomic.

Are you still with me? Then let me say that any niggles are dwarfed by the sheer programming excellence of this set. If you can learn to program it elegantly, you'll be rewarded with a simpler flying experience compared with other radios, with fewer switches needed to control the different phases of flight. And once you understand how the 4000 works, you can throw the manual away because at its heart, the 4000 is actually very simple, with most of the features working in a totally generic way.

From a personal point of view flying F3F models, I simply cannot contemplate giving up the 4000. The system allows me to trim the models out quicker, and to tailor every aspect of my models operation to my taste. It is also built like a tank and has been rock solid and trouble free for four years.

In short the mc4000 is a milestone system. I can't see any modeler outgrowing its flexibility. Multiplex themselves will be hard pressed to surpass the 4000, which is why if you have one, hold on to it for dear life, and if you need one, take my advice and place your order now!