HDP-121A Microphone Impedance???

[Ed Richards]

I believe it is 50kohms. Anything above that would act pretty much the
same. That is why they don't specify a particular Z.
Ed Richards

On Sat, 22 Apr 2000 16:57:57 EDT "John H. Klingelhoeffer"
<WB4LNM at AOL.COM> writes:
> Fellow Heathens:
>
> I have a Heath HDP-121A microphone that I would like to use with a
> from-scratch transceiver that I am building.  This is the "old"
> desk-standing, grey cased microphone (I think sourced by Shure) that
> was sold
> as the desk mike for the SB and HW series transceivers.
>
> I'd like to present the optimum input impedance to the microphone to
> give it
> the best response.  I have the original instruction / specification
> sheet for
> the microphone, and it only states that the microphone impedance is,
> quote,
> "Hi-Z".  Not quite specific is it ? !   I am presuming if this were
> a "low Z"
> microphone, such as that used on solid state transceivers that "low"
> would be
> 200 to 600 ohms.
>
> I'm guessing from taking a look at the input circuit on my HW-18
> (which used
> the same series of microphones as the SB and HW series) that what
> the
> microphone would "like" to see is maybe something around 100k ohms
> or more.
> Some phono inputs are set at 47K ohms, and that would also be "high"
> in my
> thinking, relative to 600 ohms.
>
> Anyone know what "Hi-Z" translates to for this microphone?   Thanks
> in
> advance for your responses.
>
> John...
> WB4LNM
> One of the Hams from Heath (1979-1981)
> Gambrills, Maryland
>
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