[Elecraft] Microphone Re-wiring Astatic D-104

[Joe Subich, W4TV]

Don,

Here is the link to a circuit by Paul, W9AC in response to some
questions I asked several years ago:
        http://72.52.250.47/images/D104.jpg or
        http://72.52.250.47/images/D104.pdf

This is a single component modification for the D104 and K3.

For a D104 that has been butchered with a Heil HC4 element, the
G3SEK preamp circuit is more appropriate:
        http://www.ifwtech.co.uk/g3sek/in-prac/best-of.htm#icom
Note: the K3 handles the HC4/HC5 butchered D-104 without any
preamp when the K3 is configured for FP.H and no bias.  However,
the G3SEK preamp permits using the butchered D-104 with a computer
sound card "Line" input when the mic input is unusable because
of internal noise.

73,

    ... Joe, W4TV


On 11/24/2012 11:09 PM, Don Wilhelm wrote:
> Alan,
>
> This is the FET mic preamp that I promised.
>
>
>
> Alan,
>
> The 4 pin vs. 8 pin is not your only problem. For pin to pin
> connections, I suggest you consult G4WFW microphone connection database,
> it is quite helpful.
>
> The D-104 microphone element is quite high impedance, and some have
> suggested simply using a series resistor to mitigate the high vs. low
> resistance microphone impedance situation, I would suggest that a simple
> FET stage could solve the problem.  The D-104 mic feeds the gate of the
> FET and the output is taken from the source (or drain). There was a web
> reference to the Heil FET amplifier that was recommended, but I have
> lost it.  I have it on my hardrive and will send it to Alan in a
> separate email. -- the reflector will not accept html nor any other
> resential
>
> 73,
> Don W3FPR
>
>
> On 11/20/2012 9:21 PM, Alan Slusher wrote:
>> Colleagues:
>>
>> Am looking for assistance in rewiring an Astatic D-104 Astatic microphone
>> (T-UG9 stand) for use with my K3 and K2 transceivers. The mic is
>> presently
>> wired for 4-pin Ten-Tec.
>>
>> Any assistance would be greatly, and gratefully, appreciated.
>>
>>
>> Alan V31FA
>>
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