[Elecraft] KX3 PC Headset Stereo mike

[Dominic Baines]

Thanks Peter,

I will play with a set of RCA terminated leads in a similar way and 
measure voltages. It could be that the tolerance in the position of the 
1st and 2nd ring on the mike plug are slightly different (was a cheap 
headset), magnified there is about a 0.2mm difference between the one on 
the headset and the audio plug or that on a typical stereo plug grabbed 
from the junk box.

I have a feeling it might be better to build a unit that uses a 4 
connector plug and plug that into the KX3 and the the headset into that, 
and then any hand held or foot PTT?

What is odd as with a mono mike (both headsets are the same just one has 
a mono mike plug) I had to do nothing in the KX3 menus and and both VOX 
and PTT on the KX3 operated without having to alter either.

I think the drawings are 99.99% complete but missing a few minor things 
especially the details for the inter connections as you have discovered 
as well.

72

Dom
M1KTA

On 13/05/13 15:13, Peter Eijlander (PA0PJE) wrote:
> Hi Dom,
>
> When I plug in the mic of my PC-headset I can operate the vox without 
> any problem. MIC BTN=off and MIC BIAS=off...
>
> When I measure the mic connection with a standard 3.5 mm. stereo cable 
> with two RCA plugs at the other end, I end up having no voltage on the 
> tip of the 3.5 mm plug and 2.4 volts on the middle ring. That is the 
> situation I'd expect it to be: These mics are usually wired for mic 
> inputs of soundcards and they carry the bias supply voltage on the 
> middle ring and the AF output comes from the tip.
>
> Switching on the MIC BIAS ads an audible noise on my monitor as does 
> setting the MIC BTN either to PTT or to PTT UP.DN.
>
> Of course in the MIC BTN=off you have no PTT function on the plug 
> available, so use of VOX is the only option to transmit.
>
> In fact the PTT function is off but the logic level stays high and 
> that supplies the microphone with the necessary bias form the VPTTUPDN 
> line that comes straight from the PIC U10 via a 1k resistor if I 
> understand the schematic part 'KX3 Control Panel: Connectors' right.
>
> I don't know whether J8 in the drawing signifies the MIC connector but 
> I doubt that for it does not have that extra ring on on the MH3 
> microphone plug for nothing. I looked through all drawings but could 
> not find that connector.
>
> Maybe someone else can fill in the gaps...?
>
> 72/73,
> Peter - PA0PJE
>
> dombaines at yahoo.com schreef:
>> HI,
>>
>> KX3, I have played about with the two mike settings BIAS (on/off) and
>> pgupdwn/ptt/off with a computer headset where the 3.5mm mike has a
>> stereo plug and no joy. Noted it initially as got the PTT error message
>> and TX stays open when plugged in. No amount of combinations of with VOX
>> on/off and setting the mike options seems to make it work where pressing
>> the PTT on the KX3 keys the mike (or VOX does).
>>
>> A stereo to mono adapter doesn't seem to help.
>>
>> Anyone had a similar problem and got a cure?
>>
>> The headset is identical to another I have as I wanted to get a second
>> set (for second KX3) but the earlier one has a mono mike.
>>
>> I looked at chopping the cable and rewiring (The mike has a tiny + screw
>> in it so I undid it just to see how it was wired) but I noted the wires
>> are not the easy to solder type.
>>
>> 72
>> Dom
>> M1KTA
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>