[Elecraft] Microphone Re-wiring Astatic D-104

[Paul M Dunphy]

On 11/25/2012 12:09 AM, 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
>>

     Last Friday I wired an amplified  Astatic D-104 with a T-UP9 stand 
for my K3.  I assume the wire colors are standard . . . if not, then you 
might have to dig further.  All you need are 4 of the 6 wires in the 
cable.  Cut off the 4-pin DIN plug and replace it with a standard 8-PIN. 
  Cut the black and yellow wires off flush as they are not needed.  Then 
wire as follows:

White (TX audio) - Pin 1
Red (PTT) - Pin 2
Blue (PTT ground) - Pin 8
Bare braid (audio ground) - Pin 7

(See page 13 of the K3 manual for the pin locations)

     This works fine on my rig.  I have used an amplified D-104 on 
various rigs for 27 years (on a TS-940, a TS-450, a FT-847 and an ICOM 
PRO3.)  I have worked all DXCC entities on SSB except one with a D-104. 
  Change the 9-volt battery in the base every year or so and you won't 
find a better mic for DXing.  They got the false reputation of being a 
CB mic in the 1970s.  This is not their heritage, and they have been 
around in the commercial and amateur field since the 1930s . . . Astatic 
stopped making them in 2002. However, they are a classic and will work 
well with you K2/K3.

     Just crack open the amplifier pot on the bottom enough to get a bit 
of audio, and then use the rig's mic gain and compression to get the 
desired audio.  I never used any amplifier other than the stock one in 
the T-UP9 base.

     So far I have only made 3 SSB QSOs with this, and over 600 CW QSOs 
in the contest this weekend.  What a fantastic radio, and I've just 
scratched the surface!

73, Paul VE1DX  (K3 #6949)