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Solar charge controller QRM mitigation?

Discussion in 'General Technical Questions and Answers' started by KB7KJY, Oct 10, 2019.

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  1. KB7KJY

    KB7KJY Ham Member QRZ Page

    Hey Everyone,

    I am diving back into Amateur Radio after a 19 year break..... I am a little behind the curve..... Be patient with me..... :)

    I am planning out my radio install for my RV and running into unexpected issues. I was not anticipating any QRM issues as the RV is a 37' diesel pusher. No ignition noise and the alternator is 35' from the radios. All was good until I fired up my solar charge controller (MPPT).

    I am finding that I have a variety of QRM generators in my kit that weren't around my shack 20 years ago.

    My question: Does anyone have experience with quieting MPPT charge controllers? Specifically the Midnite Classic?

    I can tinker with it myself. A little trial and error with chokes and caps. Unfortunately all of my ham/electronics gear, parts and pieces went away. I am starting from scratch. It would be fantastic if I could get some direction from someone who has already been there.

    I haven't tried out my inverter out yet. I may be asking the same questions about my Xantrex 1800/24 inverter.

  2. WR2E

    WR2E Ham Member QRZ Page

    Kind of an odd name for a piece of solar power equipment, isn't it? :)

    Sorry, can't help ya, just hadda comment on that.
  3. KB7KJY

    KB7KJY Ham Member QRZ Page


    I am missing the funny?

    I need another cup of coffee :)
  4. KF5LJW

    KF5LJW Ham Member QRZ Page

    Been there done that. Do quite a few off-grid systems for telecom tower sites. Problem is the controller itself. There are only two I know of that play well with HF and I doubt you can use the Genasun unless your panel wattage is 150 watts or less. Really the only manufactures and models good for hams are Morningstar TriStar or ProStar line-ups.

    Genasun is the only one certified and tailored to the Marine market to be used with Nav/Com. Being made for marine market means it is hardened. But the catch is the largest controller they make is GV-10 limited to 150 watt input and 10-Amp output.

    Morningstar products go up to 60-Amp output.They do NOT have that noisy fan like Midnite Solar has because they do not get as warm. Almost as good as Genasun.

    What you might try is add common mode chokes to both Input (panels) and Output (battery)
    Last edited: Oct 10, 2019
  5. WR2E

    WR2E Ham Member QRZ Page

    Maybe? but not really funny, just an odd choice I thought.

    Not 'classic', the OTHER word... "Midnite" … Sun ain't out at midnite at most latitudes.
  6. KB7KJY

    KB7KJY Ham Member QRZ Page

    :) Midnite (not midnight) is the name of the company.
  7. KB7KJY

    KB7KJY Ham Member QRZ Page

    Looks like I have some conflicts in my plan......

    I have 1800 watts of solar.

    I am drawn to the Midnite Classic is that I am significantly over-paneled for my battery bank. The Classic, been used in conjunction with the Whizbang Jr., will allow me to limit the current into the batteries while making full output available to your loads.

    This is kind of a big deal. Without that feature I would have to manually turn panel strings on and off depending on conditions. If I were stationary it would not be such a big deal. I may be in Seattle tomorrow and Phoenix on Saturday. I sized my panels for worst case.

    I am going to have to stretch my brain a little. I haven't had my fingers in radio of this sort in 20 years. I will do some refresher reading and see what I come up with.... Common mode chokes.....
    Last edited: Oct 10, 2019
  8. KB7KJY

    KB7KJY Ham Member QRZ Page

    OK. I have it figured out in principle.

    The wire from the panels to the combiner will be 10ga. And the wire from the combiner will be 4ga.

    Now to figure out which cores will be appropriate for my application.

    Thanks again.
  9. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Make sure you apply those cores as Common Mode chokes which means both the positive and negative cable from the device you're choking has to pass through the core. If you try clamping separate cores on the positive and negative cables separately you'll be choking the differential mode currents independently and your cores will likely saturate when driven by the H fields created by currents flowing in those lines.

    When you run both cables through a choke you're primarily choking the common mode currents which is what's left over after the positive and negative currents and the magnetic fields they create cancel each other because the currents are flowing in opposite directions.

    IOW, size your cores so you can run both cables through each one.
    KX4Z likes this.
  10. VE7BPB

    VE7BPB Ham Member QRZ Page

    I have a solar power system that I use on some of my radios and my MPPT controller causes quite a bit of noise on HF. In fact, watching the SDR waterfall at around 7 Mhz is fascinating, you can see the noise sweeping back and forth as the controller tries to optimize it's charging.

    If you can do a little bit of pretty simple electronic building you can make a completely RFI-free linear controller, as opposed to the switching that causes all the noise on modern controllers. It may not be quite as efficient as an MPPT controller, but you say you have some extra capability in your system and the nice thing about the linear controller is that you can easily size it for any amount of amperage just by choosing a bigger relay.

    A very interesting read:

    regards, Roy
    K0UO likes this.

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