UPS Noise

Discussion in 'EMC Matters' started by Ian G4ELW, Mar 1, 2020.

  1. Ian G4ELW

    Ian G4ELW New Member

    Afternoon all.
    I have a problem with a Leibert PSP650MT3-230U UPS causing lots of noise on 80m.
    Have tried mains filters a la GM3SEK etc but I am convinced that the QRM is being radiated from inside the unit itself - interestingly it starts causing QRM when the mains supply is switched on irrespective of the on/off switch on the front panel
    It's a few years old now and I would happily replace it but who knows if a new one would be better, worse or the same.
    Just wondered if any forum members have had good or bad experiences with any of the small (approx 400w) UPS's that are available nowadays?
    Which also makes me wonder if there is potential for a members database of equipment used and good/bad experiences.
    We all use these things along with monitors, printers, back up drives etc so if they cause QRM then why not tell people?
    Just at thought
    73
    Ian
  2. Ken G3SDW

    Ken G3SDW Moderator

    Well i have not come across one of these before and i run the society's EMC Help Desk so i am sure that i would of heard of a troublesome one by now.

    You mention about the problem being there whether or not the mains switch is off or on, from that i would assume that it is not just a mains switch but a standby switch, i may be wrong of course.

    It maybe radiating from within but more likely to be conducting the RFI into the mains supply and that is radiating from your mains wiring.

    Simple options, strip it down and replace all the mains filtering components, or as you say its a few years old now, not sure how old it actually is but either way just replace it as if this is the first time this has happened then i am sure any new updated models will be OK, if not and a new one causes the same problem, most unlikely, then you have the right to send it back.

    Hope this is of some help.
  3. Ian G4ELW

    Ian G4ELW New Member

    Thanks Ken
    Yes, there is a standby switch on the front of the unit but the issue occurs when it is switched on at the mains supply irrespective of the standby switch position
    I have coiled the mains lead around one of the large 'problem solver' ferrite cores mentioned by GM3SEK as close to the unit as possible but the QRM does depend on how close the unit is physically to the rig (have tried a few different positions now)
    It's around 6 years old now so probably time to replace it but was interested to see if anyone had similar experiences
    Appreciate your help!
    Ian
  4. Ken G3SDW

    Ken G3SDW Moderator

    Just reading on more detail about this unit then i would expect as it has battery back up that the battery is flat and is trying to, charge its self to charge its self.

    I would investigate that first as it clearly states that the batteries life expectancy is approx 2
    years, just a thought.
  5. Ken G3SDW

    Ken G3SDW Moderator

    Ah 6 years then back up battery is flat as a pancake, you now have the task of weighing up the cost of a new battery against a new UPS
  6. Ian G4ELW

    Ian G4ELW New Member

    Yes - I think this needs 'knocking on the head' so will probably but a new complete unit.
    Will let you know how I get on
    73
    Ian
  7. Ken G3SDW

    Ken G3SDW Moderator

    Look forward to that Ian, but i do not think you will have any issues.
  8. Ian G4ELW

    Ian G4ELW New Member

    Hi Ken
    You were correct of course.
    Bought a new unit from Canford and show a screendump using it with a charged battery (so in bypass mode)
    Vast improvement - just a couple of minor carriers at 3510 & 3529.
    Really appreciate your help
    73
    Ian G4ELW

    New UPS.jpg

    Attached Files:

  9. Ian G4ELW

    Ian G4ELW New Member

    Sorry - that was a bit larger than I thought !
  10. Ken G3SDW

    Ken G3SDW Moderator

    It's all my pleasure Ian, could not see any reason why a new one would give you any problems.

    Finally thank you for letting me know as sadly many don't keep me updated so thank you for that as it enables me to complete my bi monthly report.

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