Digital Crawling – Spektrum DX6 Setup Text & photos by Jay Kopycinski

With the introduction of the Spektrum DX6 radio set hobbyists got a six-channel system to add greater capabilities to their crawlers. Those with skill enough to manipulate twin flight sticks can use this setup to gain glitch-free spread spectrum transmission and a tiny, lightweight receiver. Most drivers will choose to use one stick for front steering & front axle throttle control and the other stick for rear steering and rear throttle control. The advantage of independent steering is readily apparent. Also, having independent control of the drive power to each axle allows the driver to hold one axle in brake mode while the other steers and claws the ground, turning the crawler sharply. This “dig” capability is very useful in tight turns and having the ability to drive the axles independently can also be beneficial when, for instance, you want the front to pull up a ledge but not have the rear driving forward as much, pushing the rig towards rolling over backwards. Here will show you how to program your DX6 to gain the four independent steering/throttle functions, but also allow you to combine (mix) the two throttle channels to use them simultaneously for much of your driving. To begin with, install the receiver in the crawler and connect the power supply (regulator or ESC BEC) to the battery input on the Spektrum receiver. You do not need to hook up ESCs or steering servos at this point

For this example, we’ll setup the transmitter in the following configuration: Throttle – Channel 1 – Front ESC Elevator – Channel 3 – Rear ESC Aileron – Channel 2 – Front Steering Rudder – Channel 4 – Rear Steering Depending on your preference, you may want to switch the front/rear channels from left/right.

It is a good idea to remove the wheels and tires from the gearboxes to make setup easier. This will allow you to run the motors and easily observe their behavior as you perform the radio setup when setting the throttle adjustments. Let’s get started. We’ll essentially be using pages 49-51 of the Spektrum DX6 manual to program the radio for independent/dependent throttle control of the front and rear gearboxes.

Turn on the radio system.  Press SCROLL and INCREASE buttons simultaneously to enter Function mode.  Press SCROLL until “MIX A11” is displayed on the screen (see figure).

Press the channel button twice to display “MIX A CH”. Press INCREASE to select the Master Channel (we will use Channel 1). Press DECREASE to select the Slave Channel (we will use Channel 3). From this point on radio should display “MIX A13” to designate we are mixing Channel 1 (front ESC) and Channel 3 (rear ESC). Press CHANNEL once until “MIX ASW” appears. PRESS INCREASE or DECREASE to select the switch used to enable the mixing function. We chose to use the F1 (flap switch), located on the upper right corner of the transmitter.

Turn the F1 mixing toggle switch to ON (pull toward you). Press CHANNEL once until “MIX A” appears along with the mixing value (%) on the screen. To set the mixing value for the Slave Channel, hold the Master Control (left) stick fully forward and use the INCREASE/DECREASE buttons to set the mixing value to +100%. This should make both motors run at the same speed. Repeat this action with the stick fully backward to set at +100% for reverse. (Make sure to set the forward and reverse mixing values to positive numbers.)

Hook up the two ESCs and steering servos to the appropriate receiver outputs. Following the directions provided with the ESCs, calibrate them to the stick movements on the radio to set full forward and reverse throttles, and the neutral point. Do this with the F1 mixing toggle switch ON so both ESCs will be program matched together.

Further notes: Adjust digital trim as needed on master or slave if one motor tends to start rotating sooner than the other. Also, with mixing enabled, check the forward and reverse throttle positions. If the motors rotate opposite directions under one of these conditions, check to make sure the mixing values are set to positive values when the Master Channel is in both the forward and reverse positions (moving stick fully forward and fully backwards).  With this programming you should now have independent front and rear throttle control, and be able to tie both controls together with a flip of the toggle switch. If you want to do "dig" or "burn" turns, just throw the flap switch down and drive the front wheels only while turning. You may want to note, this setup works much better with brushless motors than brushed motors. If lathe (brushed) motors are used, the rear motor won't lock up, limiting the holding power of the rear tires during “dig” turns. Have fun crawling with your newfound capabilities! Thanks to Kevin Guhman of The Crawler Store for his assistance in putting these programming instructions together.

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