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

[Eugene Balinski]

I am sure that someone has mentioned this before however,
has someone located a good source of matching plugs for the
mic and headphone jack on the KX3?   I would like to order
some in advance and start some projects. 

73

Gene K1NR
KX3 S/N TBD   : -)





On Thu, 08 Mar 2012 21:15:06 -0500
 Don Wilhelm <w3fpr at embarqmail.com> wrote:
> For those who do not understand the technicalities, I
> would suggest that 
> the CM-500 cannot be plugged directly into the KX3 jack.
>  The KX3 PTT is 
> on the ring connection, and the stock CM-500 connects the
> Tip and ring 
> together for the AF connection.
> 
> It MAY work, but it is not a certainty, the KX3 function
> of the ring 
> contact is three-fold - PTT, UP and DWN.
> the audio level on the ring may or may not induce one of
> those functions 
> depending on the voltage and current.
> 
> It would be better to create a homebrew adapter that
> would accept the 
> CM-500 AF on the tip and ring, and connect that only to
> the tip of the 
> KX3 jack, and at the same time add a small box with a
> pushbutton for PTT 
> and also pushbuttons (with the appropriate resistors) for
> UP and DWN).
> 
> In other words, the stock CM-500 *may* work, but it may
> not depending on 
> the levels presented at the ring connection.
> 
> This situation may also be present in microphone designed
> primarily  for 
> computer use - they may be OK, but if they create funny
> PTT or UP or DWN 
> conditions, blame it on the connection between tip and
> ring on the 
> microphone jack.
> 
> 73,
> Don W3FPR
> 
> On 3/8/2012 3:46 PM, Joe Subich, W4TV wrote:
> >> 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
> >
> >
>
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