PMP Power Starvation

Hello Everyone,

I thought I would share some observations from the field, so that you might recognize these symptoms and quikly firnd the problem  I recently had several of my customers install a 24V based power supply to power the CMM, PMP450 and or ePMP1000 access points, and to charge some backup battries.  The problem came from the lower than suggested voltage starting point of 24 VDC.  By itslef, it should not be a problem, but coupled with ethernett cable runs at near max distance and batteries that needed some of the power to charge themselves...and strange things started happening.  The symptons we observed, and they varied by site, were in all cases some of all of the access points had very poor range.  It seems the transmitter couold not come up to the full power se set it to.  In extreme cases we saw access points not responding to management, or only doing it intermittently.

Remember, the synchonized ePMP1000 and the PMP450 Access Point ship with, and expect to see 30VDC from the power supply.  While they can run with lower vloltages, doing so requires the tradeoff of shorter cable runs to compensate.

So, you think you might be seeing these symptons, how can you be sure?   For a first step, I'd want to be 100% certain the max cable distances have not been exceeded, and that there are not any excessive splice points in the cable.  If those are certain not to be the problem, try disconnecting a probem AP from the CMM, and powering it directly with a wall plug power supply - even the one that powers the PMP450 subscriber radio will do for a brief test.  if thisng are suddenly better, yoou have confirmed the problem.

It seems there are a few very popular battery backed up 24V supplies out there.  If you want to use one, make sure the current capability is sufficient, and consider using a 24 to 30V DC converter in line.  Meanwell makes a few that should work nicely.  It will reduce the battery run time during power outages, but in trade you'll know your APs are all running like Cambium intended them to. 

Happy Multipointing.

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