[Elecraft] [K3] Fw: Non Amplified D104

[Don Wilhelm]

The non-amplified D-104 microphone is a great one for frequency response 
*if* it is working into a very high impedance (50k to 2 megohms).
Unfortunately, the input impedance of the K3 and most other modern 
transceivers is in the vicinityof 600 ohms, so the D-104 will  sound 
very bad when used directly with those transceivers.

You could use a single FET stage behind the D-104 (it will easily fit 
into the base) to match the impedances and it will sound good.  
Otherwise, it is a 'museum piece'.

Others have suggested a simple series resistor (something on the order 
of 100k should do) to allow the stock D-104 to drive low impedance 
transceivers - the crystal (or later ceramic) mic element produces lots 
of voltage. I have not tried this technique, I am just passing along 
information received.

73,
Don W3FPR

-.-. --.-N3TU -.-. --.- wrote:
> I tried a non amplified D104 and it  was not good at all. The audio was real
> low when the mike was at 60. It had a slight "fan noise" and I had no fans
> running. The mic was wired up right because when I put it back on my ADI
> radio it worked well. My ADI radio hand mic works on my K3. ADI and Kennwood
> wiring is the same. Now the non amplified D104  is a museum piece in the
> shack. 
>
>
>
>
> George & Jan wrote:
>   
>> I presently use a D104 that I modified using a rubber mounted Radio Shack
>> electret element. With bias on it works well. Reports on air are good.
>>
>> Reports using the crystal element were poor.
>>
>> George
>> AI4VZ
>>
>> Anyone ever use the non amplified D104 mic? If you have, how does it
>> perform
>> and what's it look like on the scope?  Does it sound good and natural
>> without sounding like you are talking in a trash can? How do you compare
>> it
>> to other mics.
>>
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