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Mic mod im sure its done before on bearcat 980

Discussion in 'CB Radio Modifications' started by Rwb, Oct 30, 2018.

  1. Rwb

    Rwb Well-Known Member

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    20181028_083429.jpg 1540737071265_20181028_083422.jpg 1540737071529_20181028_083330.jpg 1540737017815_20181028_083321.jpg
    I opened the mic,a few friends said i could use more modulation. Inside the mic was this felt kinda covered baffle and it had like a heavy 1/2" bandaid kinda looking plug over the small hole your voice goes into the white ring.
    After a few radio checks i tried the baffle completely removed n was told too much. Im thinking of boring the hole out a small bit n trying it.
    Any suggestions if i should or shouldnt go farther? Its like a 3/16" hole was thinkin of opening it to 1/4". If it dont work mix up some glue n rebore it to factory diameter.
    Everybody said i added a good bit of louder modulation and voice was clear but could use just a tad more.
    Did it to both of my bearcats. I was on lsb ch 39 talking about 45 miles to 65 miles the farthest base from me


     
    Shadetree Mechanic likes this.

  2. binrat

    binrat WDX Club Coordinator
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    If it wss me, slightly larger hole with all the guts put back in.
     
    Rwb likes this.
  3. Robb

    Robb Yup

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    You mean taking out the spit pad?
    Been there; but is no substitute for a better mic element . . .
     
    unit_399 and binrat like this.
  4. Rwb

    Rwb Well-Known Member

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    It had a sticker thing like a real heavy bandaid about half inch in diameter on the black disc or baffle covering the small hole.removing it did lots im leaving the cloth like pad but enlarging hole is next.
    The photo of the bandaid got removed somehow in my phone
     
  5. Handy Andy

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

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    That was a good find.

    As you can see the "element" is a typical dynamic but what I found interesting was why did it have to get baffled in the first place.

    I haven't taken my 980 out of the box yet - maybe I should as time permits.

    ... could be HIPPA ting...
     
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  6. Rwb

    Rwb Well-Known Member

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    i did 1 mic this morning .i was told you got it right this time. Used quarter inch bit then deburred with my pocket knife.ended up almost 5/16" but without it they said sounds screwey.
    Makes me think mod mic then tune radio
     
  7. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Reminds me of the mic on my FT-2800. There’s a little disc in the hole over the element, removed it and the reports were how much better the radio sounded. So I’ve always ran it that way, what little I’ve talked on it that is.
     
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  8. Handy Andy

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

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    I've come across several Midland Hand mikes with their cradle design having several weird things done to the element it houses.

    Some even have a plastic "baffle" which looks to be part of the element - but when you finally break it apart - the baffle completely misses the diaphragm and itself "bounces" thru into the element. So the mic itself had one "flavor" of audio - when converted - the results had a far more natural sound to it.

    They called this a noise cancelling design to remove breath and wind noises, giving you performance for clear communications. No matter what the environment you work in- throws at you (paraphrase).

    The Midland 77-115 and 77-113 had these - what a wreck...
     
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  9. kopcicle

    kopcicle Well-Known Member

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    offset the hole and make it larger...
     
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  10. Rwb

    Rwb Well-Known Member

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    I got great reports from 5 who live diffrent distances from me this morning. The 980 might let the 99v rest up a tad.got 1 more mic to fix in the mornin.
     
    Redbeard U812 likes this.
  11. Redbeard U812

    Redbeard U812 Active Member

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    I have an old Road Devil that lost the screen and what ever was there. Mic works but after reading these posts I am coming into a design. The mic is loud compared to a 646 noise canceling. If creating a baffled design improves the sound I'm all for it. I like the offset hole design to deflect wind, maybe just a little foam in there will improve the NC.

    Let's see here:
    -cut section of my vacuum cleaner extension tube off at about 1/2" to 3/4" length
    -round divit cut from a milk carton to match the OD of the vacuum cleaner extension tube with an offset hole of 3/16" dia.
    -foam from the AC register filter in the camper
    -glue gun to connect all plastic parts to the mic

    .........
     
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  12. Rwb

    Rwb Well-Known Member

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    and we have a new design mic.this might be your calling make you rich
     
  13. Shockwave

    Shockwave Sr. Member

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    If you ever want to convert a radio that uses a dynamic stock mic into "sort of" a power mic, there is an easy trick using an electret condenser element in place of the lower output dynamic. Replace the dynamic with a condenser that is powered by lithium button cells to form between 6 to 9 volts. Feed that bias trough a 2.2 k ohm resistor. Use a .022 to .047 uf cap to feed the audio back into the mic wire. Adjust the sound to your liking by adjusting the value of the cap. Larger caps give more bass but be careful not to go into distortion or sound "muddy" with too much bass. Punchy audio with good fidelity can be achieved on most radios that were designed for a dynamic stock mic.

    Since the cap now feeds audio directly into the mic wire, you can re-purpose the unused pole of the mic switch to turn the battery on and off when the mic is keyed. The 2.2 k resistor value can be changed to adjust gain with values between 1 k and 4.7 k. Maximum gain occurs when this value best matches both the output impedance of the element and input impedance of the radio. Keep leads short to avoid RF pickup and place a .001 uf cap right across the back of the mic element if it tends to feedback from RFI.
     
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  14. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Any possibility that cap across the element would work to reduce talkback feedback on a Galaxy chassis where the 470k resistor trick doesn’t work?
     
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  15. Shockwave

    Shockwave Sr. Member

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    Hello Pork Chop,

    The feedback you describe sounds like it's the result of the speaker not being fully muted in the TX mode. The cap on the back of the element is designed to remove RF interference that would make the mic "squeal" and would not help in your situation.
     
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