Re: Dynamic mic on ubitx

Michael Shreeve

On Sat, Feb 24, 2018 at 8:02 PM, Raj vu2zap <rajendrakumargg@...> wrote:
Has to work and work it does. I proposed this for Bitx40 as I needed more gain for my Yaesu mic.
 in uBitx it is possible to put a preset to control mic gain.


At 24/02/2018, you wrote:
>Dave wrote,
>"Modifications to use a Dynamic Mic.
>Referring to the uBITX Schematic.  The Gain of the Mic PreAmp is controlled by R63 in the Emitter of Q6 to C62/R64.  It basically decouples the audio bypass of R64 by C62 to limit gain for the high output Electret Mics.  Replacing R63 with a Zero Ohm resistor and putting a 10K at the Mic input should allow a Dynamic Mic to work now with a Mic Gain Control.  Also R60 that supplies Mic BIAS to the Electret-Condenser Mic needs to be removed.  If there is not enough Gain still, you might have to reduce the value of R64 to maybe 470 Ohms or so.  If you cannot look at your transmitted signal on a scope at least listen to your audio on another receiver to verify you are not causing distortion.
>More Gain for the Electret Mic
>To simply get more gain with an Electret Mic you might try dropping another 47 Ohm chip resistor on top of the existing R63 by soldering another chip resistor one end at a time.
>Dave WI6R"
>Has anyone actually performed this mod?  Does it work?
>73, W9KJO

Michael Shreeve N6GRG
15901 Cloverdale Road
Anderson, CA 96007
"Don't worry about a thing, 'Cause every little thing gonna be all right!" -Bob Marley

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