Has anyone else had an issue with Cambium PMP450 APs where one of the polarities starts to get weaker - it's hard to detect until someone has an issue, but it usually manifests for us as a sudden, drastic change in the Signal Strength Ratio (V-H) on the AP, for all connected SMs. Normally, it's pretty close to zero, as long as there is traffic, but when the problem manifests, the typical value will shoot up to anywhere from 8 to 20dB (absolute value, since sometimes it's the Vertical Polarity, other times it's the Horizontal). I built an MRTG tracking page for this value for a few LUIDs on each AP, and it has brought the problem to our attention for some APs, but we only catch it when we are looking, and the fact the values are unpredictable if no traffic is flowing makes this a difficult graph to read..
Here's the thing - we've had six APs with this issue. We take them down and replace just the AP (same sector antenna, it doesn't get moved, same antenna leads, etc.), and it always fixes the problem. We have also done bench tests on the troubled APs, taking care to keep every single thing about the test precisely the same, other than the AP, and we can duplicate the same failure mode - it follows the AP, and the AP alone. Unfortunately, even though there's a common failure mode, these didn't all have the decency to fail during their first year of service, and we haven't had any luck getting them repaired, either. Are we seeing something unique, or has this happened to anyone else? Just wondering -- Darren
