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Old 22 January 2011, 11:13   #1
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Icom M411 mic water/fault

I'v had an Icom M411 set on my rib for two years now, and have just found out that when seawater gets on to the face of the mic, it make audio weak and muffled.
If the face of the mic is dried out with a cloth, it goes ok, but thats no use at sea if you don't know its happening!
I dont think water gets into the fist mic itself, but there is a very small white hole on the top right face of the mic (designed in). It seems possible that water is getting in there or blocking the hole, causing the fault.
Looking at the pics of the new m411, the mic is slightly different, ie different up & down shaped buttons.
Have Icom fitted a new mic which addresses this problem?
I,m sending my set back to hopefully have a possibly upgraded mic fitted? or whatever is needed. So we'll see what happens.
Anyone had similar probs with the HM164-B mic on these supposedly waterproof radios?

Thanks
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Old 22 January 2011, 11:16   #2
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Any water on a small microphone will affect its performance. I think that's why some of the newer handhelds have some sort of vibrate feature to clear water off before use. Whether that is for the speaker or mic, I can't remember though.
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Old 22 January 2011, 11:28   #3
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Seems the Aquaquake is only for the speaker. The audio is really bad at times, surely it should be up to the task if its sold as a quality waterproof set. Its not good if your life depended on it.
I'd like to know if Icom have discovered this possible problem, or does the problem lie somwhere else on the set?
Trouble with intermittent problems, they somtimes can be hard to proove or diagnose.
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Old 22 January 2011, 11:34   #4
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happens all the time, blow down it of bash it on your leg, failing that take it to bits and use an airline at about 25psi
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Old 22 January 2011, 11:42   #5
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Do the new mics do it, just incase my airline does't reach The Skerries?
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Old 22 January 2011, 12:10   #6
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Quote:
Originally Posted by Sun-dry View Post
Do the new mics do it, just incase my airline does't reach The Skerries?
they get bunged up with all kinds of stuff if they're left in the open, when i do the yaght racing we use the radio a lot, normally the radio is bad to start with but after a day or so it's fine, then you leave it a few month's it's back to crap, don't know the answer to new mic's i just abuse it for a while and it's ok till the next time
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Old 22 January 2011, 21:01   #7
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Happens pretty often. I slap mine against the opposite palm to clear the water and allow the diaphragms to vibrate the way they're supposed to.

BTW, it affects both the mic and speaker in handsets that have both.


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Old 23 January 2011, 05:16   #8
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I think the pick-up itself might be a piezoelectric microphone element (approx 7mm diameter, which is soldered onto the internal PCB), maybe if the 2mm hole in the mic face where the element is glued directly behind, gets blocked with water, the voice vibrations can't reach the element properly, thus producing a muffled sound. I'm only guessing here!!!

My mate suggested hot-melt gluing some very fine plastic mesh/gauze over the hole, to disperse water befor it can enter the hole.

Maplins also sell mic socks for about 3, which might be able to be adapted to fit over the mic itself, and also cut down on that wind noise at the same time.

At tho mo though, i'm just banking on Icom having upgraded their mic to eliminate this problem a little bit more professionally!
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Old 23 January 2011, 13:07   #9
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I think what happens is that the speaker cone (which acts as a a microphone diaphragm when transmitting) gets water on it, making it much heavier than normal, which attenuates the higher frequencies. That creates the "muffled" sound in both directions (transmit and receive, assuming an in-mic speaker), or what's transmitted for a mic-only handset.

I believe the diaphragm actually is sealed around the edge, protecting the electronic parts from water intrusion from the outside of the mic (else it wouldn't work very long in the marine environment.)

At least, that seems to be the case with mine (Std Horizon mic/speaker) and my buddy's (Icom console mounted VHF, non-speaker mic)

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Old 23 January 2011, 13:49   #10
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Yes, thats prob whats happening,(mines a mic only).
The prob is how to cure it, without having to bash/blow it every time I use it.
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