Electret microphone for K3

[Alan. G4GNX]

Sometime back I bought a W2ENY electret conversion kit for my Astatic mic but I seem to have lost the bias resistor/jumper that came with it and there’s no value specified in the instructions.

I see that the bias resistor used with the Elecraft MH2 microphone is specified as 5K6. As I want to use the (converted) Astatic with my K3, I wonder if this value seems sensible to maintain the correct bias and prevent max bias current going over 10mA?

73,

Alan. G4GNX

______________________________________________________________
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
Message delivered to [hidden email]

[gm3sek]

It isn't a problem, because the FET preamplifier normally operates in the saturated region where it approximates a constant-current load, in effect drawing only the current that it "needs". Typically Idss will be only a few hundred microamps. With typical resistor values and supply voltages, neither value is critical.

73 from Ian GM3SEK

>-----Original Message-----
>From: Elecraft [mailto:[hidden email]] On Behalf Of
>Alan. G4GNX
>Sent: 10 March 2017 22:49
>To: Elecraft Reflector
>Subject: [Elecraft] Electret microphone for K3
>
>Sometime back I bought a W2ENY electret conversion kit for my Astatic mic
>but I seem to have lost the bias resistor/jumper that came with it and
>there’s no value specified in the instructions.
>
>I see that the bias resistor used with the Elecraft MH2 microphone is
>specified as 5K6. As I want to use the (converted) Astatic with my K3, I
>wonder if this value seems sensible to maintain the correct bias and prevent
>max bias current going over 10mA?
>
>73,
>
>Alan. G4GNX
>
>______________________________________________________________
>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
>Message delivered to [hidden email]

______________________________________________________________
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
Message delivered to [hidden email]

[Don Wilhelm]

Alan,

With the K3, you do not need a bias resistor at all.  Just go to the
MENU MIC SEL and set it to aply bias - that is what the 'b' means.

73,
Don W3FPR

On 3/10/2017 5:49 PM, Alan. G4GNX wrote:

> Sometime back I bought a W2ENY electret conversion kit for my Astatic mic but I seem to have lost the bias resistor/jumper that came with it and there’s no value specified in the instructions.
>
> I see that the bias resistor used with the Elecraft MH2 microphone is specified as 5K6. As I want to use the (converted) Astatic with my K3, I wonder if this value seems sensible to maintain the correct bias and prevent max bias current going over 10mA?
>
> 73,
>
> Alan. G4GNX
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

______________________________________________________________
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
Message delivered to [hidden email]