[Elecraft] [KX3] MIC Bias has no effect

[iain macdonnell - N6ML]

On Sat, Apr 19, 2014 at 9:27 AM, dmb at lightstream.net
<dmb at lightstream.net> wrote:
> I'm connecting a Yamaha CM500 headset to the KX3, and find that the
> microphone works properly regardless of the MIC BIAS setting (MIC BTN is
> set to OFF).
>
> As I recall, the few times I used the CM500 w/ the K3, the MIC BIAS had to
> be ON or the microphone produced no output.
>
> Any idea why the MIC BIAS setting doesn't seem to matter w/ the KX3?

I measure 2.36V on the ring of my KX3's MIC connector, even when MIC
BTN is off. The CM500 is designed for use with PC sound cards, where
(at least sometimes) the bias is delivered on the ring instead of the
tip. I actually find that the CM500 audio is hotter when bias is
turned OFF in the KX3.

73,

    ~iain / N6ML