[Elecraft] XLR microphone to K3 wiring

[Joe Subich, W4TV]

Ron,

> I am guessing that I want unbalanced audio. The scheme I have 
> seen for this is pin 2 for signal, pin 1 for ground, and that 
> is jumpered to pin 3. The 1/8 inch tip to XLR pin 2 and sleeve 
> to XLR pin 1. 

The rear panel mic input does not ground the sleeve of the 
1/8" (3.5mm) jack - it is raised by an RF choke.  You will 
want to use twisted pair wire with pin 2 of the XLR connected 
to the tip of the 1/8" plug and pin 3 of the XLR connected to 
the sleeve.  

If you use shielded cable, connect the shield to pin 1 of the 
XLR and bring it out as a flying lead to the ground terminal on 
the K3's rear panel.  Do not jumper pins 1 and 3 of the XLR 
unless the "low side" of the mic input is connected DIRECTLY 
to ground/chassis.  Doing so will add hum and noise to the input 
signal (the "pin 1 problem"). 
 


> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Ron Kenwood
> Sent: Friday, October 24, 2008 2:41 AM
> To: Elecraft
> Subject: [Elecraft] XLR microphone to K3 wiring
> 
> 
> I want to connect a mic with a 3 pin XLR connector on its 
> cable end to 
> the rear panel of my K3. No instructions came with the mic. This will 
> require a female XLR to 1/8 inch mono connector. I have seen 
> a couple of 
> different ways that mics may be wired. Balanced or unbalanced and 
> apparently there can be some variation in which pins are used 
> for what.
> 
> I am guessing that I want unbalanced audio. The scheme I have 
> seen for 
> this is pin 2 for signal, pin 1 for ground, and that is 
> jumpered to pin 
> 3. The 1/8 inch tip to XLR pin 2 and sleeve to XLR pin 1.
> 
> Does this sound right?
> 
> Ron W3ZV
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