Ken wrote: I was told by a friend that the K2 prefers a 600 ohm mic and that a electrec mic element wouldn't sound right. I've got both - an old Cobra (label removed) CB 600 ohm dynamic and a boom headset salvaged from a cell phone (2.2k).
---------------- A typical electret does very well on a K2. Electrets are not necessarily a high-impedance element. The impedance the rig "sees" will be the value of the dropping resistor used to supply d-c bias to the mic element "hot" side. Since the d-c voltage source for the bias is grounded for audio (has large capacitors to ground in the circuit), the resistor becomes the audio load between the audio line and ground. My electret uses a 1k resistor, so its impedance is 1k ohms. It is true that a high-impedance mic won't normally sound good on a rig expecting a fairly low impedance mic, like the K2. Connecting a typical high-impedance mic to a low impedance will normally cause the lows to be lost, making the mic sound very "bright" or "tinny". Very few such mics are still around. Even the venerable "D-104" was updated with an amplifier in the base to convert the very high (appx 0.5 megohm) impedance of its crystal element to the lower impedance most current Ham rigs want. My mic is 'homebrew' - using an inexpensive (< $5 USD) electret element mounted in a hand mic enclosure that originally contained a cheap dynamic element. The electret element has a frequency response far, far greater than the K2 needs: from about 30 Hz to about 16 kHz. The transmitted bandwidth is controlled entirely by the K2's SSB module filter. People tell me it sounds excellent on the air. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [email protected] 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
