[Ken Streeter]

Originally Posted by Alan Anderson

Wow. I've been going from the official IFI documentation which says the Victor deadband is 117-137. I never gave it a second thought. But that would perfectly explain the asymmetric PID response I wrestled with a week ago.

Add our voice of experience to testify that the "true neutral" we have seen on the Victors is at 132, rather than 127. We repeated this test with many Victors from the last three years and have found all of them to have a true neutral of 132 rather than 127. Similarly, the "deadband" range is actually 125 to 138 (an average of ~132) rather than 117-137 as described by IFI's documentation.

For PID control, the difference in a "center point" of 132 vs. 127 makes a huge difference. We have confirmed this with many victors from the last few years. For software control, we are certain that you do NOT want to run the IFI "calibration" procedure, but instead should simply use a center point of 132, with a "deadband" of 6-7 units.

A past thread from Mike Betts which provides a graph of some detailed tests he ran to confirm this is in this post from 2005.

We don't know whether the source of the error (132 vs 127) is due to the PWM signals being generated that way by the RC, or if the problem is in the Victor itself. We don't have an oscilloscope to track down the source of the issue, but our empirical studies are quite conclusive that 132 is the appropriate center point for PID control loops.

--ken