uBitx mic gain
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Hello everyone! I am currently playing a little with my Ubitx and I have an issue which bothers we since the beginning. The microphone gain is not pleasing me. I literally have to scream into it for having a conversation with somebody. I have modified R65 from 1K to 4.7K and R63 from 47 ohms to around 20, can't remember the exact value. I can say the mod works but still not how I want. Can someone advise me about this matter? I am also considering altering the bias resistor for the electret mic. I have made some experiments with a cheep-chinese audio amplifier running on 3.7 V and I have made my conclusion that I have the best gain and clearness of the sound if I bias the electret mic with exactly 10K resistor, not 7 not 11. I am not an expert in electronics, this is just what I have noticed. Is there a chance to get some more signal from the uBitx mic by changing the bias resistor?
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I did mod only R63 to 24ohm. You may want something like the VOGAD compressor where you can whisper and have full output. Attached you find a simple schematics by Barry. The original data sheet by Plessey is even simpler. I made one in an external box but still to test in the next days. I have a mil surplus manpack using a VOGAD and works very well, I am surprised why such a simple and effective design is not a standard in ham radios. Il 20/dic/2018 18:29, "Daniel" <gonewiththeego@...> ha scritto: Hello everyone! I am currently playing a little with my Ubitx and I have an issue which bothers we since the beginning. The microphone gain is not pleasing me. I literally have to scream into it for having a conversation with somebody. I have modified R65 from 1K to 4.7K and R63 from 47 ohms to around 20, can't remember the exact value. I can say the mod works but still not how I want. Can someone advise me about this matter? I am also considering altering the bias resistor for the electret mic. I have made some experiments with a cheep-chinese audio amplifier running on 3.7 V and I have made my conclusion that I have the best gain and clearness of the sound if I bias the electret mic with exactly 10K resistor, not 7 not 11. I am not an expert in electronics, this is just what I have noticed. Is there a chance to get some more signal from the uBitx mic by changing the bias resistor? |
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For mike gain, add an to the mic circuit. Think of this as more along the lines of audio compression than as gain per se.? You will want to put a small elecrolytic cap between this board's output and the mic wire from the mainboard, as that line has voltage on it that this add-on board may not appreciate.? This board has exciter voltage on it's microphone input (since it comes with eletret element itself, that you will remove) so that your line from the hand mic can go right to it. I chose to include a 50K trim pot soldered right to this board for level control. It makes a hell of a difference in a good way, from signal reports. It takes me from being in the noise, to at least readable copy or from readable copy to "I can't believe you're only running ten watts!". Give it a try.? I also use one of these boards on the speaker line just before the volume pot. With three selectable gain levels, you can choose how much "help" you want for either application. |
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