Hitec Laser 6
Hitec Ranger III FM
|Two 1-axis joysticks or one 2-axis joystick|
|3rd channel: proportional (not just On-Off)|
|3rd channel: ATV or EPA|
|Ability to manipulate all 3-channels at once *|
|* 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.