[Elecraft] CM500

[Mark n2qt]

nice write up on sound card microphones (like in the CM500) at

http://www.hobby-hour.com/electronics/computer_microphone.php

My CM500 just came today, haven't confirmed anything yet.

Mark n2qt

-----Original Message----- 
From: Jim Brown 
Sent: Thursday, January 13, 2011 1:37 PM 
To: elecraft at mailman.qth.net 
Subject: Re: [Elecraft] CM500 

On 1/13/2011 8:24 AM, Tommy Alderman wrote:
> SOMEWHERE in my pile of papers I have a CM500 headset owners paper!
> Can someone please tell me what the tip and ring connection are for the
> microphone? I assume the base is the ground connection.

Audio appears between tip and shell. As nearly as I have been able to 
determine, the ring contact is not used at all. Tip also needs a 
resistor (about 5K ohms) to V+. Turning on bias in the K3 does this 
internally, so no resistor is needed.  I had to add the resistor in an 
adapter that I built to use with an FT1000MP at PJ4.  The bias resistor 
is also built into the mic input of most modern computer sound cards. 
The CM500 works just fine in my Thinkpads.

73, Jim K9YC
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