If you have a working, unamplified D-104, the solution to this is quite simple.
Back in the 1990s, my transceiver was a TS-830S. I had a pre-citizens band D-104. These classic microphones were much heavier than the later ones and had a stamped serial number plate riveted to the head. The output of these microphones was very high and, when connected to an input with an impedance of a few tens of thousands of ohms, the frequency response was very strident. The Astatic data sheet for the D-104 contained a graph, with curves, which showed how a lower impedance load suppressed the mid range and bass response. Inside the base of the push to talk stand, I placed a 787 kilohm,, quarter-watt, metal film resistor in series with the hot side of crystal cartrige output. The D-104 no longer sounded shrill. The response was silky smooth, as determined by transmitting into a dummy load and recording the audio from a second transceiver. As a bonus, I could then run my mic gain at eleven o clock, rather than nine o clock. This made it much easier to set the mic gain properly, as the control was not so touchy. I was actively DXing, back then, and the slightly modified D-104 did a great job of breaking pileups. I was often complimented on my audio and often asked what microphone I was using. Gary, K0CX “Most D-104 mikes are not suited for use with today's radios.? The original D-104 was designed to work into a load impedance of 4 meg-ohms or higher.? Today's radios microphone input is about 50k ohms or so.?? The result is then excessive load on the D-104 element.? This is the major cause of frequency response issues. Bob McGraw” -- This email has been checked for viruses by AVG. https://www.avg.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
