[Elecraft] Astatic D-104 Microphone

[Don Wilhelm]

I might add that if one has an amplified D-104, but wants to remove the 
dependency on the battery in the base, that single FET addition can 
replace the amplifier in the mic.  Yes, I have done that in one of my 
D-104 mics.  It also works for the K2 when the microphone configuration 
header is wired for the Elecraft MH2 microphone (with the bias resistor).

73,
Don W3FPR

On 1/28/2014 8:58 AM, Joe Subich, W4TV wrote:
>
> The easiest way to use an unamplified D-104 with the K3, or replace a
> bad/noisy transistor preamp is this single FET circuit from W9AC:
> http://72.52.250.47/images/D104.pdf
>
> The single FET is uniquely suited for the high impedance crystal
> element and "bias on the mic" power.  When handled properly the
> Astatic crystal element is far superior to the commodity dynamic
> elements sold at tremendous mark-up by the "name" amateur vendor.
>
> 73,
>
>    ... Joe, W4TV
>
>