SB 101 MIC IMPEDANCE??

[Ed Richards]

Rob;
The exact point at which an impedance is considered "high" is somewhat
arbitrary. It is commonly considered to be above 25k to 50k Ohms. 600
Ohms is defiantly NOT high impedance. It is considered "low" impedance.
Heathkit transmitters work best with a high output crystal mic, although
a high impedance dynamic mic will work too, if the output is sufficient.
Avoid carbon and Electret mics as they are not only low impedance, but
require an excitation voltage also. A crystal mic will usually measure
"open"  on an ohmmeter. A high impedance dynamic mic should measure in
the high hundreds or low  thousands of ohms. Impedance and resistance are
not the same thing. A 50k Ohm dynamic mic might measure only a thousand
Ohms on an Ohmmeter.. Hope this helps.

73,
Ed Richards

On Wed, 21 Jun 2000 10:45:35 -0700 Rob Ellis <ac6wq at YAHOO.COM> writes:
> Hi all, I have SSB xmit trouble . Rig was tested ok on
> SSB by previous owner whom I know to be reliable.  I
> wired up my "flea market" Electro Voice mic per the
> book and had about 4-5 watts RF output. I'm suspect
> that I have the wrong impedance mic.  What is
> considered high impedance? For example I have an old
> Yaesu mic that's marked 600 ohm, is that high
> impedance?  Your comments appreciated. Rob
>
> =====
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