Two Iron core chokes (either side of DC SSR)

Discussion in 'Wireless & RF Design' started by Art, May 23, 2016.

  1. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
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    61
    Hi Guys :)
    I’ve been winding a lot of chokes lately to measure what I attenuation I get out of them with a signal generator & scope.
    This is mainly to help me make a table of a readily available but undocumented Iron powder core toroids available locally.
    Over 3 different size cores, my results have been filters from 39MHz down to 530kHz.

    I’m wondering now if you used a choke on the input of of a DC SSR, and another on the high current load output
    (obviously a higher current choke on that side), would they sum like inductors in series,
    or would one attenuate superimposed AC on the signal even further than the other?
    Cheers, Art.
     
  2. crutschow

    Expert

    Mar 14, 2008
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    The there is little EMI generated on the input to a SSR, so I don't see that putting a choke there will have much effect.
    Certainly it will have little effect on any EMI generated by the output.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Where are you expecting to get those frequencies from?, chokes are usually used in various switching circuits of which a SSR output is just an ON/OFF condition.
    Max.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    But an SSR can generate a pulse of EMI when it is turned ON or OFF.
     
  5. Art

    Thread Starter Distinguished Member

    Sep 10, 2007
    785
    61
    Hi, yes I wasn’t talking about the edge of the DC relay switching, but maybe the load itself.
    I might anticipate a choke used on the DC power supply of a linear amplifier for example.
    If there were other equipment behind the switching of the DC SSRs,
    it might provide peace of mind to use another choke of the same frequency to further attenuate RF again at the SSR input side.

    I can’t say that I’ve tested whether superimposed RF is effectively isolated by the
    DC SSR (from the switching input to the load terminals) the way DC would be.
     
    Last edited: May 23, 2016
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Very rare to use a common mode choke or other on a DC SSR.
    Normally the equipment behind it is isolated via the SSR.
    What type of load are you anticipating for the SSR?
    Max.
     
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