Audio Response with the FT8900 Yaesu MH-48A6J

Posted on Feb 5, 2014

Gently work a small screw driver around the mic element rubber boot, and slowly work it out from the mic front casing. Be gentle and take your time. I found that there was a spot near the top of the mic housing where I could work the screwdriver in to get things started. Lift the mic element out of its housing when you have it loosened up. 9.Using a 1/16 inch drill bit, drill out the two existing holes in the front of the

Audio Response with the FT8900 Yaesu MH-48A6J
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microphone and the third fake one. Then slide the drill bit back and forth to transform the three holes into a slot. (See the picture below for an idea of how this will look when you are done. ) 13. Wad up a tiny bit of cotton and place it inside the mic housing where the baffle was. Use enough to loosely cover the bottom of the little chamber that houses the electret. This helps to act as a pop filter. Using too much may result in a muffled sound, you really just need a few wisps. 15. Mount the circuit board inside the front of the microphone and tighten down the screws. Then wad some cotton to fill the mic housing. This microphone seems to have some odd acoustic resonances from the hollow space in the back of the microphone. The cotton will reduce this effect greatly. The worst culprit regarding restriction of the low end audio appears to be in the speech amplifier built into the remote display head of the radio. A circuit diagram for the PANEL-SUB-UNIT is located on the back of the MAIN UNIT block diagram. One glance will reveal that they have coupled the output of the mic through a. 0056 uf capacitor to the input of the first stage of the speech amp. A larger value would have produced much smoother response, and much more audio. However, this circuit board is populated with devices that are the size of a flea, and I would not even attempt to mess with it! All is not lost though, you can still bring about some...

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