Why PCM
Why the range test is an important indicator with PCM
These days, top-level modellers use PCM. Frankly, I can't think of one who doesn't. The reason is simple - PCM provides superior control for our sophisticated models. FM is fine for sport models, but as sophistication grows, so does the need for PCM. While some mature modellers are still leery of PCM- due to lock-out experiences with other brands 15-20 years ago - today's PCM equipment can't be beat for keeping your model under control. That having been said, it's also true that PCM can, and will, go into "hold" (or fail-safe- a preset user programmed position) if it does not receive the correct coded signal for a given period of time. Symbolically, one could think of going into hold as the same thing as "going over a waterfall". The purpose of the range test is to give us an indication of "how close we are to going over the waterfall". Good ground range indicates that the system is strong - it will take considerable interference from outside sources to cause the model to go into hold. Poor ground range does not mean the model will crash, only that it is more susceptible to outside interference - the smallest interference might cause the system to go into hold. Because models are so tough to come by, personally I prefer robust ground range!
The System.
Normal technique for range testing calls for the operator to wiggle the stick, and a helper to determine whether the system is working or not. Problem is, they aren't connected. The helper doesn't know what inputs are being provided, so determining when the signal is lost is murky. To address this issue, the method suggested here uses the fail safe part of your radio to determine the exact point where the radio loses range. By programming the elevator to kick "up" when the signal is lost, it becomes perfectly clear where the exact point is - allowing us to quantify the results. In a sense, this is a parallel to choosing a .9 volt/cell cutoff point for battery conditioning.
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