Thanks for putting me onto N4JK's article on the modified D-104.
Are you using the Astatic cartridge on your 104? I have an old D-104 carcass
somewhere in the bowels of the shack that I wish to restore. However, it needs
a new cartridge. Are NOS Astatic 104 cartridges, crystal or ceramic, still
available? If not, I may have to go the Radio Shack condenser mic route as per
Art's other "web site" article.
>" Yesterday a ham friend of mine reminded me that I had some time in the
> past mentioned seeing an article on modifying a D-104 for use on
> lower-impendance mic input rigs... and that he wondered if I remembered
> about the article. Well, fact is I had and that a few weeks ago I
> actually stripped out the stock preamp in my circa 1980s D-104 and
> installed my home-brewed version of the MPF-102 based amp detailed in:
> My only modification to the circuit was the addition of a resistive
> attenuator in the output as it was initially a bit too strong for my
> Omni-VI Plus. In short I was more than pleased with the results with the
> modified D-104 on my Omni-VI Plus. I had made recordings before and
> after and there simply wasn't any similarities whatsoever. The stock
> D-104 was tinny, thin and even somewhat distorted. The modified D-104
> was full without being muddy and had the necessary peak around 2kHz to
> add voice clarity.
> Anyway, back to yesterday. I told my friend that I could do one better.
> I asked him to meet me on 40 meters (he lives about 10 miles away in San
> Francisco) and that I would demo the modified mic. Before I got to the
> modified D-104 I began the on-the-air test with my newly installed
> boom-mounted Heil Dual Element HM-10 (I had just used the Heil
> microphone on the previous weekend for the SS SSB contest). My friend
> immediately commented that my audio was really nice. I changed from the
> HC5 to the HC4 element and he respoinded kindly. I changed microphones
> to my Ten-Tec 700 hand mic and he said that it was nice but not
> particulary distinguished. I then put on the modified D-104 and got a
> rave review. In fact an easedropping ham friend of mine came on
> frequency and echoed how great the modified D-104 sounded. Just to
> illustrate the difference I placed a stock D-104 on and they cringed."
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