I go with RON on this one.
After 30 years working ( under contract) with companies
that include Sennheiser, AKG and Shure Brothers, all who
actually manufacture microphone elements. They taught me some things.
I have bought a few Sennheiser boom headsets on Ebay... great headphones ,,
and i have some mics for my K2 icoms and tentecs made from
electret elements scrapped from telephones...nortel, panasonic.
ALL electrets are WAY TOO GOOD for communications audio....
even the one you get at radio shack for $ .99 US. Just stuff it in a gooseneck
and you have a GREAT base station mic.... don't forget the ptt switch...
another $ 1.29.....
It's Sooo cheap you owe it a try.
bill
----------------
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
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