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Galaxy dx2547 power supply

Discussion in 'CB Radio Modifications' started by Larry A McClanahan, Aug 11, 2018 at 11:18 PM.

  1. Larry A McClanahan

    Larry A McClanahan New Member

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    I bought a DX2547 to verify that my channel kit will work in it. I checked the voltage to the power supply in the radio. As per other radios I have had that contained a switching power supply, the max voltage available is 13.6. I changed out the resistor that is nearest the VR control. It tested at 3. 2K. I replaced it with a 3.0 k. And that raised it to 14.45. The power output of the radio is greater and so is the modulation.


     
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  2. Dmans

    Dmans Well-Known Member

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    Larry,
    That's great! I am sure there is a point of "diminishing returns". Where exactly is that threshold? At what point do components suffer?
    (I am asking because I do not know the answer. Not asking to be an Ass.)

    73's
    David
     
  3. Larry A McClanahan

    Larry A McClanahan New Member

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    Don't know. But I do know that 14.45 is still within a safe range.
     
  4. Larry A McClanahan

    Larry A McClanahan New Member

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    The radio has a jack on the back of it so that you can run it on a power supply or run it in a mobile. I hooked it up to the power supply at 14.5 and it worked fantastic. I have never run any mobile on base at 13.8.
     
  5. Larry A McClanahan

    Larry A McClanahan New Member

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    I would imagine 15 volts and Beyond is too much. I never go past 14.5.
     
  6. Dmans

    Dmans Well-Known Member

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    Larry,
    Good information to have.
    I have a "Like New" 139XLR that I know needs re-capping, new voltage regulators etc. There appears to be some corrosion (conductive glue?) around the power supply section. My thoughts were to bring the voltage up during this repair a tad to keep current to a respectable level. (Not sure what the output DC is at this time). And to upgrade regulators and components as needed/recommended etc. All of this is "food for thought" for an upcoming project.

    (The radio works well now. I am having a hard time starting to "fix something that isn't broke". ;))

    73's
    David
     
  7. Larry A McClanahan

    Larry A McClanahan New Member

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    It is nothing but a mobile with a power supply. When they switched to switching power supplies, they did not engineer their own power supply. They took what was available. And what was available at a cheap price was one that only puts out 13.6. All I did was raise the voltage up less than 1 volt. No harm coming from that. They also put a low rated voltage regulator on the radio. I always upgrade that. They also put low-grade capacitors on some of the main components. I also upgrade those. When you upgrade those, you take some of the load off of the regulator.
     
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  8. Larry A McClanahan

    Larry A McClanahan New Member

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    Perhaps a 3.1k would be good middle ground, but 3.0 is what I had.
     
  9. sunbulls

    sunbulls Well-Known Member

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    I also replace all the incandescent wheat bulbs with soft white defused LED’s. That takes a lot of the load off. During receive, those old school wheat bulbs draw substantially more current than an entire receiver section. I found this upgrade especially important while running emergency batteries or solar cells. The other option I used on another radio was simply adding a switch to turn those bulbs off. I’m sure Apollo 13 could have benefited if LED’s were invented before their time.
     
  10. Larry A McClanahan

    Larry A McClanahan New Member

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    Yes, that would have made a world of difference when they were trying to get back to Earth on minimal power. They also learned a lesson about the oxygen scrubbers. They should all be the same size and shape. But they still to this day carry duct tape to the Moon.
    Most of the newer radios, if not all of them, use LEDs now. But I totally agree. I do the same thing.
    The switching power supplies on the DX to 547 have a sticker on them that says output, 12 volts. They just turned the variable resistor to its Max, which is 13.6 volts.

     
  11. Larry A McClanahan

    Larry A McClanahan New Member

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    and just for the record, It does not have to stay at 14.45. You can turn the output down to the level you desire on the variable resistor that is on the power supply after the modification.
     
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  12. Larry A McClanahan

    Larry A McClanahan New Member

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    I set it at 14.2

     
  13. Larry A McClanahan

    Larry A McClanahan New Member

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    14.45 was what it was doing after the mod and the VR was still set all the way up where the factory set it but only putting out 13.6. So this is a good mod for these.
     
  14. Larry A McClanahan

    Larry A McClanahan New Member

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    But you have to be careful. I believe there is more than one power supply they are using in the DX 2547.
    For record-keeping purposes the power supply is marked RS - 100 - 12 with a sticker on the power supply
     
  15. Martian

    Martian Active Member

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    They did use more than one but for the most part they used a meanwell supply.
    It's a 100 watt supply.

    That radio already has a marginal power system as it is.
    It's not a radio that I would try this on. There is virtually no margin on the AM regulator in AM and none in SSB mode.
     

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