Gus, I think the term bias, or bias voltage is a pretty generic term when meaning applying a voltage or current to turn on a device, in this instance a microphone element that requires voltage to operate. http://www.learningaboutelectronics.com/Articles/What-is-bias-voltage 73 Gene, N9TF
----- Original Message ----- From: "Augie \"Gus\" Hansen" <[email protected]> To: [email protected] Sent: Wednesday, January 6, 2016 1:02:58 PM Subject: Re: [Elecraft] Koss SB-45 Headset, update on comfort Hi Jim, > Electret and dynamic mics are equally good for ham radio. Use whatever > comes with the headset you like and be happy. All that matters is that > electret mics need bias turned on and dynamic mics do not. Do you know why Elecraft calls the power provided to an electret element BIAS? Unlike the large form condenser microphone elements that need both polarizing potential and preamp power, usually provided via a "phantom power" circuit, an electret element is permanently polarized. The power applied via the phantom circuit is actually providing only the drain voltage for the FET preamp in the electret microphone capsule, not any kind of biasing voltage. Of course we have similar terminology used in systems that provide control voltages or operating power to remote equipment: The so-called BIAS-TEE used to inject and extract power over a coaxial cable, for example. I haven't found any official documentation for these types of circuits that uses the BIAS moniker. Are there any references that you might point to? Cheers, Gus Hansen KB0YH ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
