[Elecraft] bias for Yamaha CM-500

[Hector Padron]

I have my CM-500 that arrived yesterday directly to the radio rear mic input and the BIAS enabled at "rP.L bIAS" and it works great.Don't know how many volts the K3 produce in that setting but the headphone set works very good.
 
AD4C
 


"For a refined ham it is compulsory to own a k3"

--- On Sun, 1/17/10, Don Wilhelm <w3fpr at embarqmail.com> wrote:


From: Don Wilhelm <w3fpr at embarqmail.com>
Subject: Re: [Elecraft] bias for Yamaha CM-500
To: "David Christ" <radioham at mchsi.com>
Cc: elecraft at mailman.qth.net
Date: Sunday, January 17, 2010, 1:11 PM


David,

It is not critical.  Look at the reflector post by Jim Brown in the last 
couple days - I received it 01/15/2010 at 12:06 Eastern time.  Jim is 
quite familiar with the microphone and explains it much better than I can.

73,
Don W3FPR

David Christ wrote:
> I'm trying to understand the bias requirements for the CM-500 
> specifically and electret/condenser (which is it) mikes in general.
>
> Yamaha's adaptor uses 3V  (2 AAA batteries) in series with a 2.2K 
> resistor and a 1 microfarad DC blocking capacitor.   I would rather 
> not depend on batteries.  My reading of the KSB2 manual says to use 
> 10K fed from 5V while I have heard that it should be 10K for this 
> unit. I am not sure what my K3 is supplies.  I would also like to use 
> the mike with a Kenwood TS-940.  That rig has 8V available at the 
> mike connector.  So if I build an adaptor to use with that rig what 
> is the proper value resistor to use?  Or should I build a quickie 3V 
> regulator fed from the 8V and then use a 2.2K resistor?  I presume I 
> would need some value of DC blocking capacitor for the Kenwood.
>
> How does one determine the proper voltages and resistance values?  Is 
> it to get a specific voltage, current or what?  How close do you have 
> to be or is it non-critical?  What difference does it make?  Where 
> can one find information?
>
> Thanks all from an old timer who is still trying to get up to date 
> from the dynamic and crystal mikes of the 60s and 70s.
>
> David K0LUM
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