Dave,
While reading those references, keep in mind that they refer to
pro-audio microphones, which can be a bit different in their connections
and usage than mics used by hams (and consumer devices). For instance,
the pro mics are typically balanced line output, and any 'bias' required
(often called phantom voltage) is applied between *both* balanced line
connectors and the mic cable shield.
The articles are informative, but only apply partly to the microphones
we see in ham radio service.
For instance, the article will say that the basic electret element does
not need any bias voltage - that is true - but the implementation used
in amateur microphones, the element typically used contains an FET
preamplifier as part of the 'element' that you purchase. That
preamplifier does need the bias power. The basic electret element
(without the preamp) has very very low level output and would be
unusable to directly drive a transceiver. The terminology can get
confusing, but is important for understanding the subject.
73,
Don W3FPR
David Wilburn wrote:
I didn't know the answer either, so I googled it. Since I do not know
anything about the difference, I am reading these too. Not sure how
useful they are.
http://en.wikipedia.org/wiki/Microphone
http://www.pmiaudio.com/forums/archive/index.php/t-27.html
Dave Wilburn
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