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Help with Galaxy CB humming issue.

Discussion in 'General CB Services Discussion' started by Radio Face, Jun 9, 2018.

  1. Radio Face

    Radio Face Member

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    Trying to figure out this new to me old cruddy Galaxy dx44v. The radio transmits and receives fine. The problem that I am having is more of an annoyance. When i turn the squelch down I hear a audible humming sound through the speaker. The sound goes almost away when I lay the microphone down, but when I put my hand close to the mic it starts to come back. If I touch the screen on the front of the mic it gets the loudest. I can touch the mic and then touch the chassis of the radio or the mic jack and it goes away. Other mics do the same so it must be the radio. Any ideas? Thanks for the help in advance.


     
    #1 Radio Face, Jun 9, 2018
    Last edited: Jun 9, 2018

  2. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Put in some station grounds. Ground the radio to the power supply, antenna, and earth ground.
    When I say ground them I'm talking chassis to chassis and then to earth ground.
     
  3. Radio Face

    Radio Face Member

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    What's funny is my other radios don't have this issue on the same antenna?
     
  4. Radio Face

    Radio Face Member

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    Also the mic gain knob adjust the loudness of the humming sound. More gain more louder humming.
     
  5. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Sounds like filter caps in the radio.
     
  6. nomadradio

    nomadradio Analog Retentive

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    You haven't substituted the mike to see if that makes any difference.

    If the other radios don't do this, will the mike from one of those radios work on the Galaxy?

    Worth trying.

    73
     
  7. sonoma

    sonoma Sr. Member

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    nomad his last sentence claims he has tried other mics.
     
  8. sp5it

    sp5it Master of puppets

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    Switching PS? Turn power plug 180 degrees
     
  9. jon666

    jon666 Sr. Member

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    your getting a hummer lol
     
  10. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    It may not even be related to the Mic circuit - but an open line noise from a wire that's fallen off a switch on the front panel. Like NB ANL for the receiver side or like the Roger Beep - can inject a noise loud enough or make the ground plane around the 4558 chip noisy enough to pick up the hum. Especially if it's sounding like a power supply hum.

    So Volume, Squelch, NB/ANL - any audio driven line can inject the noise.

    Possible that wire or ground plane loop has showed up - usually from the radio taking a tumble off the table or got banged around more than it should - Galaxy 44's are older radio so just about anything even a loose Mic Plug Jack ring can cause the noise even with different mic's.

    So for your efforts, take the panels off the radio - especially the component side - speaker. Look around and as you can move the loom wires harness as well as the individual connector headers - looking for and listening for changes to that hum.

    Even the front panel mounting as well as side jack - both are injection points - if the front panels bezel as well as the control PCB's themselves - any loosening or recent work can cause this too - just have to reseat the panel PCB's - tighten controls' hardware and side panel screws can help.

    As you work your way thru, you may find it in the headers - to the front panel or to the main PCB. These areas are known for open traces from lines that go somewhere but are from features that are not used - just empty traces - these can eventually get coated with dust fuzz and solder lint that they may fail to ground or to a working circuit and act like antennas. Even to the back panel...

    If you can't find it in the harness, try the bottom trace side and run your fingers along the traces from the headers back to the Audio Chip, again listening for changes to the hum - it may also indicate you have a filter cap problem and the chip is more prone to noise pickup caused by the cap failure in progress.

    It's one of the hardest ones to solve yet once you find the open line or failed part - you slam yourself for not thinking if it sooner...

    I have The T-shirt with the Trophy - and I occasionally use the Sweatshirt to dust the cabinet.

    :+> Andy <+:
     
    Shadetree Mechanic likes this.
  11. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    What type of power supply are you using?
     
  12. midnight special

    midnight special Well-Known Member

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  13. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    IF someones' worked on the ECHO 2000 board in it - there may be a loose ground wire - that uses the chassis as the return - so it may be the grounding from the front panel to main PCB is poor.

    :+> Andy <+:
     
  14. Radio Face

    Radio Face Member

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    Thanks for the input. I will go try some of the things you are saying. I appreciate the time you all took to respond to post. I'm learning as I go.
     
  15. nomadradio

    nomadradio Analog Retentive

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    I have lost track.

    Have you tried another mike on the problem radio?

    Just because that mike seems to work okay on another radio doesn't mean it can't be the source of the trouble with this radio.

    If the radio behaves itself with another mike, that would be an important thing to know.

    73
     

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