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
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