A600: Radio Selection

Radio selection

Pat at Aquataur tells me he uses a Hitec Laser 6 radio. In the US, such a radio with a receiver and a couple of servos is sold as a package for about $135. But it's a shame to do this because the Laser 6 appears to over-kill. It has six channels, two 2-axis joysticks, and ATV on three channels (ATV and EPA features let you electronically constrain the range of motion of a servo). Let's look at the actual requirements:

Hitec Laser 6

Hitec Ranger III FM

Feature Any sailboat A600

Surface Frequency X X

Two 1-axis joysticks or one 2-axis joystick X X

3rd channel maybe X

3rd channel: proportional (not just On-Off) maybe X

3rd channel: ATV or EPA maybe X

Ability to manipulate all 3-channels at once * no X

* which rules out a knob on top of the radio for the 3rd channel

As you can see, the requirements for the A600 are quite beyond most sailboat requirements. The selection of radios for surface use (as opposed to aircraft) are already somewhat limited. Cars and boats just don't have the demands that airplanes do.

Feature	Any sailboat	A600
Surface Frequency	X	X
Two 1-axis joysticks or one 2-axis joystick	X	X
3rd channel	maybe	X
3rd channel: proportional (not just On-Off)	maybe	X
3rd channel: ATV or EPA	maybe	X
Ability to manipulate all 3-channels at once *	no	X
* which rules out a knob on top of the radio for the 3rd channel

I did find one alternative, the HiTec Ranger III FM can be bought for $70. It has 3-channels with the ATV feature on two. It's two joysticks control Channels 1 and 2, with a slider on top for Channel 3. Since only 1 & 2 have the ATV feature required for the winches, you would have to put the rudder on the top slider, which is an odd set-up for boat radios.

I did some research and found that the ATV feature is relatively simple to add to most modern radios. You simply add a small variable resistor, known as a "trimmer potentiometer", in line with the center lug of the joystick. You'll have to break into your radio and void the warranty to make this modification. The value of the potentiometer varies from radio to radio. For the Ranger III I came up with a value of 50K ohms by trial and error. The fix is shown below:

You must drill a small hole in the back of the case and glue the blue potentiometer over the hole. You can see the center leg of the potentiometer connected to the radio, and another leg connected to the slider. The other leg of the potentiometer is not used. The potentiometer I used is from Jameco Electronics, although you may find alternatives at a local electronics supply store. Ask for a "50k trim pot".

Remember that this particular value resistor is what worked for the Hitec Ranger III, other radios have different values. You adjust the potentiometer with a small screwdriver through the back of the radio. At it's most clockwise position, it has no effect; at it's most anti-clockwise it reduces the servo travel by 20% or so.

Configuration

Here's how Pat at Aquataur sets up his Hitec Laser 6:

Right Stick: rudder and sail
Left Stick: crewman

Here's how I'm setting up my Hitec Ranger III:

Right Stick: rudder
Left Stick: crewman
Top slider: sail

Lastly let me quote Aquataur's Pat Clear:

I use the Hitec Laser 6 as it has ATV on all channels including number 4. I would STRONGLY recommend the use of a radio with two gimballed sticks for ease of sailing.

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