[Elecraft] K2 microphone advice

[Don Brown]

Hi

The electret elements used in these mikes need to have a small bias voltage 
applied to the mike usually 5-10 volts through a resister usually a few kilo 
ohms. The 701 has the resistor built into the microphone case but the 
Elecraft mikes do not so the resister needs to be added on the back of the 
microphone connector on the front panel board. The resistor connects from 
the +5 volt to the audio out pin and Elecraft recommends 5.6K for their 
mikes. The 701 mike will work fine with or without this resistor as it would 
just be in parallel with the internal resistor and the value is not very 
critical although it does need the +5 volt supply connected for it to work.

Don Brown
KD5NDB




----- Original Message ----- 
From: "John Huffman" <hjohnc at adelphia.net>
To: <elecraft at mailman.qth.net>; "Don Brown" <DolfinDon at msn.com>
Cc: <support at elecraft.com>
Sent: Thursday, March 02, 2006 2:51 PM
Subject: Re: [Elecraft] K2 microphone advice


> What's the purpose of the 5.6k resistor?
>
> I use a Ten Tec 701 hand microphone with no resistor with good audio.  I 
> use a
> Ten Tec 706 desk microphone with no resistor but it loses some of it's 
> lows.
> Tried substituting a 9v battery fo0r the bias voltage, but it made no 
> difference
> in the audio.  The MD2 and MH2 tend to overdrive my particular KSB2.
>
> 73 de NA8M
> John
>
>
> > I use a TenTec 701 hand mike. It is a little smaller than the MH2 and 
> > comes
> > with a 4 pin connector so you will need to go to Radio Shack and get an 
> > 8 pin
> > connector and install it in place of the 4 pin. The interface is the 
> > same as
> > the MH2 with the 5.6k resistor for bias required. Works good and is
> > inexpensive ($28)
> >
> > Don Brown
> > KD5NDB
>
>