[Elecraft] [Elecraft_K3] K3, CM-500 oddity, a follow up

[Joe Subich, W4TV]

> As for the CM-500, I'd like to know if it is the tip, or ring, on the
> 1/8 inch plug that is the actual mic audio lead. I will have to try
> one, or the other, to see.

The answer is quite simple ... the tip and ring of the CM-500 mic plug
are connected together.

The supplied battery box has no connection to the ring of the mic
(3.5mm jack).  Tip of the jack is connected to tip and ring of the
3.5mm plug via a 1 uF capacitor.  The positive side of the battery
(+3.0V) is connected to the tip of the 3.5mm jack with a 2.2K Ohm
resistor.  The negative side of the battery is connected to sleeve
(common/ground) of both plug and jack (input/output).

73,

    ... Joe, W4TV


On 3/8/2012 3:16 PM, Richard Fjeld wrote:
> For the benefit to others like myself, this is a follow-up to the post below.
>
> I have been re-using an adapter made for another radio&headset-mic with my CM-500 mic.  What I didn't know is that there was a 22k resistor in the adapter that bridged the 8V to the tip and ring which were wired common.
>
> I have to admit to being ignorant of how the bias worked. I had thought the 8V on pin 6 would be controlled by the menu option.  Everything was fine until I wanted to try using a Dynamic mic with the same lashup.
>
> As for the CM-500, I'd like to know if it is the tip, or ring, on the 1/8 inch plug that is the actual mic audio lead. I will have to try one, or the other, to see. If anyone else has done this, please let me know.  It would be nice if mic plugs were standardized. Maybe the new ones are, but I don't know what it is.
>
> Thanks,
> Dick, n0ce
>
>
>
>    I bought a CM-500 less than a year ago.  A few days ago, I was trying things, and I turned off the bias, and the mic still works as if, no change.  I tried testing without tearing things apart, and I think the bias is still on.
>
>
>
>    73,
>
>    Richard Fjeld, n0ce
>
>
>