The Yaesu Mic Mod - Anyone Done It?

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03msc

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Has anyone done the microphone mod for the Yaesu MH48 mics? If you don't know what I'm talking about, view these pages:

Yaesu MH-48 Mic Modification

http://www.kf7mix.com/mh48_mic_mod.html

I'm not the best at soldering so that part makes me a little nervous. I thought about just putting some whisps of cotton or windscreen in the mic canal to see if that helps any but I haven't done that yet.

I was also wondering if there are any 'alternate' hand mics that would work in place of the MH48. My main complaint about them is how cheap they feel compared to, say, Kenwood's professional/quality feeling DTMF mic that comes with their radios, like the TM281A. It's a shame that Yaesu has skimped on their mics...

Anyway, any input would be appreciated.
 

62Truck

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Simple solution is just to back off the Mic a little bit. I have owned my 8800 for about 6 years now, only issue I have had with the mic was recently and that was the black rubber outer jacket cracked in a few places.
 

03msc

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Simple solution is just to back off the Mic a little bit. I have owned my 8800 for about 6 years now, only issue I have had with the mic was recently and that was the black rubber outer jacket cracked in a few places.
I'm told that it (well, they...this particular mic model) picks up background noise and backing off very much means the bg noise comes in the transmit. Close talking it - as is the norm for most mics - results in the breath sounds and pops from the air out of the mouth when speaking. I guess this is why I'm thinking maybe just a small amount of cotton or windscreen foam might help.

Hopefully Yaesu will redesign their mics soon...seems they are overdue for an overhaul!
 

nd5y

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There is an easier way to make the MH-48 have better low end audio without soldering.
Pull out the mic element and the rubber holder.
There is a small plastic disc between the mic element and the mic hole in the front of the housing.
The disc functions as some type of sound baffle. Removing the disc and enlarging the mic hole in the front case improved the audio on my two FT-7800Rs. On those radio the problem was the audio seemed low and tinny. The audio is now good enough that I didn't see the need to add capacitors.
 

03msc

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There is an easier way to make the MH-48 have better low end audio without soldering.
Pull out the mic element and the rubber holder.
There is a small plastic disc between the mic element and the mic hole in the front of the housing.
The disc functions as some type of sound baffle. Removing the disc and enlarging the mic hole in the front case improved the audio on my two FT-7800Rs. On those radio the problem was the audio seemed low and tinny. The audio is now good enough that I didn't see the need to add capacitors.
Did you have to switch to holding the mic farther from your mouth due to the enlarged mic hole and the disc being removed? Since I've read a few people mention the mic picking up background noise I would be afraid that removing the disc and/or enlarging the holes would make this more so. Am I incorrect in thinking that? Since you've done it then I'll trust your opinion and what reports you've received on your audio.

Where do you hold the mic and at what angle (i.e. straight on or with the top, where the channel up/down buttons are toward your mouth, etc.)?

Thanks--
 

nd5y

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I hold the mic about 2" or so away.
The angle doesn't make any difference because it is a cheap omnidirectional electret condenser mic element.
What radio are you using the MH-48 with and did it come with the radio?
The problem may be in the radio and not the mic.
 

03msc

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I hold the mic about 2" or so away.
The angle doesn't make any difference because it is a cheap omnidirectional electret condenser mic element.
What radio are you using the MH-48 with and did it come with the radio?
The problem may be in the radio and not the mic.
7800R and it's the OEM mic, yes. From reading online, and at those links, I see it seems to be a common problem.
 

FeedForward

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I don't understand the use of an IC socket if there is no IC in the socket.

As far as modifying a powered mic, it all depends upon what you are trying to do. Effective communications audio is not the same thing as high fidelity broadcast audio. Simply turning down the gain of a pre-emphasized circuit will not change the audio quality, it will just lower the deviation and decrease the S/N ratio on the receiving end. Changing parts only makes sense if you are trying to adjust a speech processor. But, one of the functions of a correctly designed speech processor is to maximize intelligibility without overdriving the transmitter. Are we working with a full set of schematics on this project? A full deck of cards, maybe?

FF
 

k6cpo

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My two FT-7900s and FT-1900 all have the same microphone and it's never been a problem for me. No one has ever commented about the quality of my audio, one way or the other. I wonder if the problem might be due to the way people hold the microphones?

Years ago, I developed the habit of speaking across the microphone rather than directly at it. This cuts down on breath noise and other associated sounds. It seems to work very well. This is radio, not a symphony. As long as the message gets across, we're good.
 

03msc

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My two FT-7900s and FT-1900 all have the same microphone and it's never been a problem for me. No one has ever commented about the quality of my audio, one way or the other. I wonder if the problem might be due to the way people hold the microphones?

Years ago, I developed the habit of speaking across the microphone rather than directly at it. This cuts down on breath noise and other associated sounds. It seems to work very well. This is radio, not a symphony. As long as the message gets across, we're good.
You have a point and I will try to speak across the mic and see if I get good reports. Since you have 3 of the radios and haven't had any problems with those 3 mics then that is good to hear. Thanks for posting! 73s
 
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