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Thread: radio noise

  1. #1
    gliderman's Avatar
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    Default radio noise

    Hi folks me again....

    need some avionics genius here.

    my radio has a crackling noise in it. however this only happens at higher power settings. it happens when i'm transmitting all the time and sometimes when i'm just monitoring the radio. Anything below 2000 Rpm and it is Crystal Clear.

    i'm wondering if i have a bad ignition lead.......

    Thoughts

    Shane-o

  2. #2

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    Default Re: radio noise

    Mine was doing exactly just that. Replaced all of the coax --- new cable and connectors.. Noise went away.
    But I would check the connection at antenna, first. A friend also had the same issue. The connector was corroded so we replaced it. Both instances prob solved.

  3. #3
    Pacerfgoe's Avatar
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    Default Re: radio noise

    how about some of these....do you have them?
    https://www.aircraftspruce.ca/catalo...sMagFilter.php
    Forrest Miller

  4. #4
    Homer Landreth's Avatar
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    Default Re: radio noise

    Quote Originally Posted by Pacerfgoe View Post
    how about some of these....do you have them?
    https://www.aircraftspruce.ca/catalo...sMagFilter.php
    Here is a statement that can be used in troubleshooting and are considering adding stuff you never had before. If you didn't need something filtered before, then why all of a sudden do you need to add a filter ? The bottom line is that 9 out of 10 times you don't need to add it because something you always had with no problem is now a problem. EMI, (Electromagnetic Interference) has two versions, Radiated, and Conducted. Radiated means something is broadcasting through the air some interference that your radio is picking up. Conducted is when something internal to the plane or the radio itself is injecting something at component level into the radio processing circuitry( like for instance a generator field winding opening up and closing and causing internal interference in the power output.) There are a couple things you can do for free. Sit with the engine off and only the radio on. Wiggle some wires, and knock on the panel area around the radio and see if anything causes your noise. If it does, then you have a conducted issue such as an internal radio problem or a connection problem with wiring or speaker or phones, whatever you are listening with. If that isn't the noise, then go borrow Cousin Vinnys portable radio (Cousin Vinnys always have portable radios) and start up the plane and see if you pick up the same noise on the portable that you hear on the aircraft radio. If you do, then you have a radiated problem so do a mag check and see if the noise diminishes with any one of the mags off.. If it does, then you are dealing with a mag or mag harness or antenna problem. If the noise doesn't stop, then pull the circuit breakers for the generator field and Buss voltage. If that stops the noise then you have a generator or regulator problem. Anyway, good luck and keep us posted. I suggest that you not go right out and buy mag filters if you have never had them before. I know here are others out there like me, who have had PA-xx airplanes flying for years without mag filters. My Tripacer is probably obscenely loaded with avionics and I don't have mag filters.

  5. #5
    CamTom12's Avatar
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    Default Re: radio noise

    Might also be electric contacts that need disassembly and cleaning due to normal, minor corrosion.

  6. #6
    piperrocks2013
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    Default Re: radio noise

    Quote Originally Posted by CamTom12 View Post
    Might also be electric contacts that need disassembly and cleaning due to normal, minor corrosion.
    I bet any money its leaking through your mags! How is the Signal Shane?? Do you hear Cracking noises on weak signals?? You can consider setting your radio squelch slightly higher. Probably fix the problem you are describing. BTW I have installed those filters as mentioned above to see 25% reduction in radio noise at the best.

    Disregard the above, you said it happens on TX, do you mean you hear it through the headset as your voice cracking?? Do you have Intercom?? Check your headsets??

    Cheers
    Jared
    Last edited by piperrocks2013; 06-14-2017 at 04:31 PM.

  7. #7
    smcnutt's Avatar
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    Default Re: radio noise

    Quote Originally Posted by CamTom12 View Post
    Might also be electric contacts that need disassembly and cleaning due to normal, minor corrosion.
    Often, the act of disconnecting and reconnecting a plug will wipe the contacts so they make a cleaner connection. The is technically referred to as 'PFM repair " aka Pure Freaking Magic. As in I took it apart and just put it back together and now it works.
    “Common sense is in spite of, not the result of, education.”
    ― Victor Hugo

  8. #8

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    Default Re: radio noise

    Quote Originally Posted by smcnutt View Post
    Often, the act of disconnecting and reconnecting a plug will wipe the contacts so they make a cleaner connection. The is technically referred to as 'PFM repair " aka Pure Freaking Magic. As in I took it apart and just put it back together and now it works.
    Where is the antenna mounted?
    If in the slipstream sometimes the antenna whips around and corrosion and loose connections can cause this problem.
    Clean everything and make certain that the antenna is well bonded with good ground etc.
    I had this as a recurring problem with an antenna mounted on the belly boot cowl.

  9. #9
    59pacer's Avatar
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    Default Re: radio noise

    Also called 're-racking'. At work, it seemed to always be the first response to an electronic issue, and often worked.

    Quote Originally Posted by smcnutt View Post
    Often, the act of disconnecting and reconnecting a plug will wipe the contacts so they make a cleaner connection. The is technically referred to as 'PFM repair " aka Pure Freaking Magic. As in I took it apart and just put it back together and now it works.

  10. #10
    gliderman's Avatar
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    Default Re: radio noise

    Hi folks
    thanks for the responses, but haven't had time to get further into this life gets in the way sometimes

    anyways on the rebuild i put new mag filters on( There where some there before but looked a lot beat up- so i put in new ones), all new wiring was installed, c/w new bus bar and breakers. new coax and new BNC connectors installed. a new sigtronics intercom was installed- to the letter of the instructions- turning it off makes no difference
    a good used serviceable ignition harness was installed. i took the generator to the local auto electric place for testing- all good
    the engine runs like a Swiss watch- with the exception of having the valve springs on number 3 intake valve break this am- all fixed now- more on this later- lol- I have a mag drop of about 75 a side- equal- ( not bad for a D2) new ones for all 4 cylinders are ordered.... Gonna be flying a fair bit in the "rocks" so i'm erring on the side of caution. my poor wallet

    Homer- I like your ideas and I'm gonna start there- thanks much

    Jared- i hear it though the headset- noise cancelling doesn't do much to help. just an annoying background crackle- only above 2000 rpm

    Shane-o

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