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Need D104 help please?

Discussion in 'Microphones, Speakers & Audio Processing' started by W4AVT, Jan 1, 2018.

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  1. KB0MNM

    KB0MNM Ham Member QRZ Page

    Re: Op never checking back to see if there was a reply on this forum:
    ERIC H LAMBERT, W4AVT
    713 DOGWOOD ST
    STERLING, VA 20164

    USA
    Someone might want to print off their point of view or input on his post, then send it to the address above ( since he did not bother to put down his e-mail address ).
    Any takers? KB4QAA, KA9JLM? KD8DEY? W9GB? Since Eric did not leave his e-mail, one could consider either of the following:
    A. Vindictive approach: Send all comments with a boat anchor and a 'postage due' USPS or UPS ( difficult, and less than moral ).
    B. Forgive Eric, yet send a short note that other folks are spending short parts of their life to be kind and attempt to help him 'do the right thing' regarding connecting the microphone to his rig. What is the right thing? Obviously, that is a matter of opinion. We all have them, and like posteriors, to others- they might stink. So it is important to point out why we would say- check QST magazine for wiring or rebuild notes ( it could save you money ) - or - find someone who really wants that particular microphone ( not just the style, the original element, etc. ) who would trade you for a finished project involving a condenser/electret ( this could save you time and make you feel better about an antique ). Maybe someone knows another amateur radio op in Virginia who would 'elmer' the 'General'.
     
  2. K4KYV

    K4KYV Subscriber QRZ Page

    Astatic deliberately put a single hole in the diaphragm of the D-104, visible under the fibreglass damper pad glued over the front of the xtal element. The Rochelle Salt crystal is dipped and covered in some kind of black sealing wax-like substance to seal moisture away from the crystal. If this seal develops a small crack or hole, the crystal quickly deteriorates.

    Rumour has it that Astatic discontinued the D-104 and replacement elements because Rochelle Salt had become unobtanium, due to EPA regulations. Suspected fake news, since crystals can be made at home using ordinary household products, no exotic substances required.

    https://rimstar.org/materials/piezo/how_to_make_rochelle_salt_piezoelectric_crystal.htm
     
  3. W9GB

    W9GB Ham Member QRZ Page

    Potassium sodium tartrate tetrahydrate, known as Rochelle salt, is a double salt of tartaric acid.
    It is still used in other industries, but crystal usage decreased in later half of the 20th century.

    During and before WW2, Rochelle crystals were used in phonograph cartridges and transducers.
    WW2 surplus created an oversupply (cheap) through the 1960s.

    The real issue has been decreasing demand, and rising cost to create (time to grow, labor) “pure crystals” for piezo-electric properties.
    ** I have not see a radio amateur offering grown crystals and restoration services. **

    The music industry (Blues harmonic players) could have “stepped in” to resolve demand/production issues — but they didn't (rock/pop guitarists preserved mfg. in 1980s for some vacuum tube era parts) — money $$ talks.

    After Astatic closed its production operations (and D104) in 2000, Kobitone in Japan became one of the remaining global suppliers of crystal mic cartridges. After the March 2011 Tōhoku (Japan) earthquake and tsunami, that supply source ended.
    Supposedly there are small operations (audiophile supported) for crystal phono cartridges.
     
    Last edited: Jan 8, 2018
  4. K5UJ

    K5UJ Ham Member QRZ Page

    I always heard the Kobitone elements weren't as good as the old Astatics.
    I was talking to one of the hams I know who works at Shure, and I somehow mentioned the Shure crystal mics they used to make and he told me they eventually quit making them because crystal elements were a lot of trouble to make. I imagine that meant, a lot of trouble to make with consistent performance specifications and reliability.
     
  5. K9STH

    K9STH Ham Member Volunteer Moderator QRZ Page

    UJ:

    The Kobitone 25LM022 elements worked very well in the D-104. However, using one involved cutting a styrofoam insert that fit into the D-104 head with a hole, in the center of the insert, just large enough to hold the cartridge. Unfortunately, Kobitone discontinued the 25LM022.

    For my D-104, I was able to obtain, directly from Astatic, one of the very last replacement crystal cartridges sold and, so far, that cartridge is still good. But, I also did obtain a number of the Kobitone cartridges (from Mouser) and made a number of replacement kits that I sold for use with the D-104. Also, I put one of the Kobitone cartridges in the Radio Shack microphone that I have on my main operating console (that I use with several different transmitters). I built a pre-amplifier (using a JFET) to use with this microphone. The microphone is used with my Collins S-Lines, with my Heath SB-Line equipment, with my Eldico S-119 equipment, with my Heath DX-100, and with my WRL Globe Champion 350A among others. The unsolicited comments, that I get, from other amateur radio operators, about the audio quality, all report excellent sounding audio.

    There are 2-things that will "wipe out" the original D-104 cartridge in a hurry: Physical shock (i.e. dropping the microphone on the floor) and high humidity. Otherwise, the cartridge will last for many decades.

    I did modify my D-104 base to install a switch that allows me to bypass the amplifier in the unit. By "throwing" the switch, the microphone cartridge is connected directly to the microphone plug. Putting the switch in the opposite position connects the cartridge to the amplifier and then the amplifier output to the microphone plug. That way, I can choose how the cartridge connects to the transmitter.

    Glen, K9STH

     
  6. KE0ZU

    KE0ZU Ham Member QRZ Page

    I've used D-104s for a long time, and currently have a head mounted to a boom, feeding a home brew amp/buffer for the station mic. I also have a desk UG8 based mic with a switch to swap Tip and Ring for use with rigs, with, and without PTT.

    Using a transformer output coupled station mic amp/buffer eliminates all the Hi-Z / Lo-Z / amplitude issues.
     
    Last edited: Jan 8, 2018
  7. K4KYV

    K4KYV Subscriber QRZ Page

    I don't use the G-stand, but mounted mine on a boom as well. A desk mic is not only a nuisance, often getting in the way on the desk; it's a matter of when, not if, it will accidentally get knocked off the table. Can't do a lot about the high humidity we have here in summer except to run the air conditioner in the shack frequently. My good xtal elements are decades old; I bought a couple of brand new ones from Astatic circa 1975.

    Interestingly, the very early runs of the D-104, circa 1933, have a large screw head in the centre of the rear plate of the head. The screw serves no obvious purpose; it's usually just held in place with a nut on the inside with nothing else attached. The original production elements must have been screw mounted to the back of the shell. A few years later according to their ads, Astatic "improved" the xtal element for better fidelity and longer life. My speculation is that they went from the screw mount to the foam rubber pads to hold the element in place when they offered the option of mounting the head directly on the mic stand without the ring and springs. With the internal foam rubber mount, the external ring-and-springs shock-mount configuration was no longer necessary, and the large screw head was retained until the supply of back places was exhausted, to stop up the unused hole. The improvement for longer life probably was to encase the crystal in that black resinous stuff to seal out the moisture.
     
  8. KA3TJI

    KA3TJI Ham Member QRZ Page

    Just an update: The second D-104 is complete and wired to work with my Kenwood V-71a. It looks great and it is a work of art that is fully functional with great audio. With two gleaming and screaming D-104s on the desktop I now need dark sunglasses to operate my station!:cool::D
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    The OP never did come back.

    What a hoot.
     

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