[Elecraft] K3 Microphone selection

[Ron D'Eau Claire]

Dave W7AQK wrote:

But I think you will 
find that many of the microphones today are overpriced.  If you want to try 
a simple experiment to see if you can prove this hypothesis, go down to 
Radio Shack and spend a couple of bucks on one of their electret elements. 
Then dig out some sort of housing for it (you probably have something you 
could use in your junkbox), and wire it up.  For very little investment you 
can have a microphone that will get you excellent reports.

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The Radio Shack 270-090 electret element has a response curve much like the
famous Astatic D-104 element with a rising characteristic above about 2 kHz
peaking at around 5 kHz, then rolling off gradually to somewhere above 10
kHz. The biggest difference is that its response extends all the way down
below 25 Hz, but the filters in the K2 roll off that end anyway. 

It makes an excellent microphone element for speech, even "hi-fi" voice. An
idea of its potential is that its response curve matches that of the best of
AM broadcasting in the USA.  

At US$ 2.79, it's pretty hard to beat. 

As Dave says, it's important to mount it well. Be sure to cushion it so it
can't rattle around. 

If you like to climb into your mic, a blast screen is a good idea. Most
microphone enclosures have one built in, even mobile mic enclosures.

Ron AC7AC