Elecraft

[KX3] MIC Bias has no effect

Classic

List

Threaded

4 messages Options

dmb@lightstream.net

[KX3] MIC Bias has no effect

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?

73, Dale
WA8SRA

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Iain MacDonnell - N6ML-2

Re: [KX3] MIC Bias has no effect

On Sat, Apr 19, 2014 at 9:27 AM, [hidden email]
<[hidden email]> 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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

dmb@lightstream.net

Re: [KX3] MIC Bias has no effect

In reply to this post by dmb@lightstream.net

Thanks to all for the responses. It makes sense, and yes, I do find that
the mic is 'hotter' w/ the Mic Bias turned off. I had already been using
the noise gate so that's probably why I didn't notice the little bit of
extra noise. All sounds good.

73, Dale
WA8SRA

> I saved this detailed note that was posted on this list a couple of years
> ago. Maybe Elecraft needs a KX3 FAQ with this info.
>
> ------------
> Re: KX3 - Buzzing in headphones varies with MON level
> Posted By: kk7p
> Date: Wed Jun 20, 2012 12:49 pm
>
> I dragged out my CM-500 to test this.
>
> The CM-500 gets its mic bias from BOTH the tip and the ring of the gray
> mic
> connector. This is too bad, because the tip voltage is controlled by the
> MENU:MIC BIAS ON|OFF but the ring is always biased by the PTT/UP/DN logic
> supply.
>
> To get around the problem, do the following:
>
> 1) MENU" MIC BIAS OFF
>
> You will find you need a lot less Mic Gain for full ALC action. In my KX3,
> I
> need about 30 if BIAS is ON, and 17 if BIAS is OFF, for full ALC.
>
> 2) Since the PTT/UP/DN is a digital logic supply, it may have some
> residual
> noise that the CM-500 passes as audio to the tip of the connector.
>
> Go to MENU: TX GATE and tap "1" to turn it ON then adjust VFO A for 01 or
> 02,
> whatever it takes to kill the residual buzz.
>
> In the case of my KX3 + CM-500, this cured the problem. And in Dave's
> case, it
> might not cure the problem of noisy neighbors, but will allow the KX3 to
> better
> ignore them!
>
> 73,
>
> Lyle KK7P
> ----------
>
> Thanks, Lyle.
>
> wunder
> K6WRU
>
> On Apr 19, 2014, at 9:27 AM, "[hidden email]" <[hidden email]>
> 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?
>>
>> 73, Dale
>> WA8SRA
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
> --
> Walter Underwood
> [hidden email]
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm-4

Re: [KX3] MIC Bias has no effect

In reply to this post by dmb@lightstream.net

Dale and all,

You will find that all computer microphones will behave the same way
with the KX3. That is because those microphones connect the tip and
ring together.
The K3 does not connect anything to the ring connection in the rear
jack, so it is not noticed.
Use the instructions provided by Lyle Johnson KK7P to use the mic
directly on the KX3. If that is not satisfactory, build an adapter that
does not connect the ring of the mic plug to the ring of the KX3 mic
jack. If you build such an adapter, you will have to turn mic bias on.

73,
Don W3FPR

On 4/19/2014 12:27 PM, [hidden email] 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?
>
> 73, Dale
> WA8SRA
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>