On 8/5/05 9:26 AM, "Roland & Elvie Whitsitt" <[EMAIL PROTECTED]> wrote:
> Probably re-hashing an old subject here. I need a hand held microphone for > the K2 and Elecraft dosn't have them anymore. What's everybody else doing? > I can't picture myself with a desk mic in the tent. And for sideband don't > really want the headphones on all the time. > Thanks! > Roland N5VWN > K2 #3090 So far so good, it's still working after my 3rd qso, The tuner just > installed and working GREAT! Spoiled by that now. Hi Roland, Because I have several Icom transceivers, I wired my K2 to match the Icom microphone pin assignments for the audio circuit and PTT (I haven't wired the up/down buttons, but may add them later). In addition to convenient interchangeability, the output level of the Icom-compatible microphones (hand, desk, and Heil boom set) is fairly high, making it easy to drive the K2 to full output and run VOX without difficulty. The electret condenser element in these mics requires power for the FET preamp in the element. I wire a 2.2K resistor to the +5 volt available on the K2 header to provide phantom power on the hot lead to the mic. By the way, there is some confusion about the DC power required by electret elements. It is not a polarizing voltage. A standard condenser element requires a polarizing voltage (typically 48 volts is used) for the condenser plus power for a preamp that raises the very low output level to something useful. However, an electret is a permanently polarized condenser, where permanent is a relative term. Most such elements are guaranteed to retain adequate polarization for at least 10 years, but 100 years is not unexpected in practice, without the need for any external polarizing source. (I'm still using Radio Shack electret elements that I bought for less than $1.50 each nearly 20 years ago. No problems.) A voltage of 2 to 10 volts is typically required to power the built-in preamp, usually an FET stage. The K2 makes 5 volts readily available, whereas the Icom rigs provide 8 volts for this purpose. Let me know if you need more information on this topic. Gus Hansen / KB0YH _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com