[Elecraft] Microphone Re-wiring Astatic D-104

[Paul M Dunphy]

On 11/26/2012 1:09 AM, Joe Subich, W4TV wrote:
>
>> Later D-104s manufactured for solid state rigs had an FET amp such as
>> Don suggests built into the base. You turn the mic over and remove a
>> few screws to see if it has the amp. It uses a 9V battery that is in
>> the base as well.
>
> The Astatic amplifier uses bipolar transistors - not FETs.  There are
> two issues with the stock amplifier ... it uses a 9V battery that does
> not last very well and the gain level is rather high (it is very easy
> to overdrive the mic input in any rig).  The schematic can be found 
> here:  http://www.nucow.com/image/D104.jpg
>
> 73,
>
>    ... Joe, W4TV
>

     I would not use the term "very easy", Joe.  It's possible, but I 
haven't done so in 27 years with 5 rigs and 3 different D-104s, all with 
the stock amplifiers in the base.  I have also got up to 5 years out of 
a 9-volt battery, but these days I change them every January just because.

      If one is concerned, one can replace the stock amplifier with the 
one(s) you described.  I am not an electrical engineer (as I believe you 
are), and all I can do is go by my experience and that of 2 other VE1s 
who have done similar to what I have . . . and we are all three DXCC HR 
on SSB.  In other words, a LOT of operating with that configuration 
because we found 25 years ago that nothing beat an amplified D-104 for 
punching through a pileup. We haven't over driven any of our rigs.  If 
you want to rag-chew, then another microphone is likely better.  I'm not 
an audiophile, and as long as my signal doesn't splatter and isn't 
distorted, I don't look for studio or FM quality audio.

     I think the OP was looking for the wiring for an amplified D-104 
with a T-UP9 base to a K3, not a schematic to make a 50-year old vintage 
D-104 work on one.  I gave him the pin-out and hookup instructions for 
the model he had.  Your points are valid, and are probably something 
that all users of older microphones should consider when trying to match 
vintage accessories to modern equipment.  I am not disputing your 
expertise or intentions.

73, Paul VE1DX