GSM Interference with Meanwell Switch mode PSU

by Zapnologica   Last Updated August 30, 2018 11:25 AM

I am having trouble with interference from a GSM modem and my switch mode PSU.

I do not know much about interference and how the radiation patterns works for GSM. Below is an image of the circuit which we build for a client. The unit worked perfectly when they previously had an external antenna installed, however it was getting vandalized, so we then installed this anti-vandalism antenna. Since then, when we close the box, the switch mode PSU dies. I assume it goes into a protection mode. And you have to cycle the power in order to get it to recover.

Installation

PSU: Meanwell MDR-10-12

Now the antenna and PSU are fairly far from one another. I can simulate the PSU behavior on another unit of mine, but putting the antenna right up against the PSU. (however it doesn't immediately die, it seems random).

Questions that come to mind:

  • Where is the interference coming from?
    • the antenna,
    • the cable,
    • the modem?
  • The PSU is connected to earth, would this not help ground the EMI?
  • I could swap the blue device & the modem around so that the PSU & Modem are not so close to one another, however my gut feel is that it is the antenna causing the issues.
  • What measures can be taken to prevent the antennas EMI from turning the PSU off?


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