Bias Resistor for microphone

[kruegerbenny]

Hello,

a friend of mine gave me an old microphone from Philips (serial no. : C944685 ; part no. : 3513 505 00692) which I want to use with my K2 transceiver. The friend said that it should be an electret microphone, so it will need a bias voltage (he said 12V, but I found in the KSB2 manual that some mic's work well with only 5V). It is also written that some mic's need a bias resistor between AF and 5V.
Is there someone who has a manual to the described mic or an idea how I can find out how to connect the mic.

Thx for your help

77
Benny
DL8NWO

[Don Wilhelm-4]

Benny,

I know nothing about that particular microphone, but the bias voltage
and resistor value for an electret microphone element is not normally
critical.  I would try a 5600 ohm resistor between the K2 front panel +5
volt line and the AF pin.

73,
Don W3FPR

On 11/2/2011 4:53 AM, kruegerbenny wrote:

> Hello,
>
> a friend of mine gave me an old microphone from Philips (serial no. :
> C944685 ; part no. : 3513 505 00692) which I want to use with my K2
> transceiver. The friend said that it should be an electret microphone, so it
> will need a bias voltage (he said 12V, but I found in the KSB2 manual that
> some mic's work well with only 5V). It is also written that some mic's need
> a bias resistor between AF and 5V.
> Is there someone who has a manual to the described mic or an idea how I can
> find out how to connect the mic.
>
> Thx for your help
>

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[Joe Subich, W4TV-4]

If the microphone is a typical electret, the external resistor
should be set for approximately 1 mA.  If the voltage source is
3.3V (industry standard for computer/AV mics) the resistor is
typically 2.2K.  With most amateur equipment the bias voltage
is 5V or 8V and a compromise 5.6K resistor is used.  In those
cases that the bias is 12-13V, 10K is a better choice.

In cases where the microphone is not a true electret element but
uses a dynamic element with a multi-stage transistor preamplifier
(Kenwood "desk" mics and Icom SM-5, SM-6, SM-20) 1 mA may not be
enough current.

73,

    ... Joe, W4TV


On 11/2/2011 4:53 AM, kruegerbenny wrote:

> Hello,
>
> a friend of mine gave me an old microphone from Philips (serial no. :
> C944685 ; part no. : 3513 505 00692) which I want to use with my K2
> transceiver. The friend said that it should be an electret microphone, so it
> will need a bias voltage (he said 12V, but I found in the KSB2 manual that
> some mic's work well with only 5V). It is also written that some mic's need
> a bias resistor between AF and 5V.
> Is there someone who has a manual to the described mic or an idea how I can
> find out how to connect the mic.
>
> Thx for your help
>
> 77
> Benny
> DL8NWO http://elecraft.365791.n2.nabble.com/file/n6954471/IMAG0168.jpg
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Bias-Resistor-for-microphone-tp6954471p6954471.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html