Astatic D104 Silver Eagle mic replacement and base PCB modification

Discussion in 'Microphones, Speakers & Audio Processing' started by KTRACKER, Aug 13, 2021.

ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: abrind-2
ad: Left-3
ad: Left-2
ad: L-Geochron



    I have acquired a D104 Silver Eagle in fairly good shape, but it needs a new mic as the original one is damaged beyond repair. I am looking for a conversion circuit design that enables me to use an electret condenser mic in place of the original but that does not require circumvention of the original mic base circuit board (I am happy to change/upgrade components on or around it, however, to accommodate the new electret mic and any improvements). Additionally, I would like the bass frequency response to be better than the original mic. I have seen a couple of designs but I think their aim was to keep the mic element original, i.e. crystal or ceramic.

    Could anyone suggest a design or two or a thread that covers what I am looking for as I don't seem to have had much with my own searches success so far.

  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page




    Thanks for your reply. I had not seen that kit but as I am based in the UK I was looking for something more cost effective for which circuit parts or a kit could be obtained here.
  4. KF4ZGZ

    KF4ZGZ Ham Member QRZ Page

    Here's a link.

    I have not personally used the kit, but have used other products of his and they work as designed.
    Also, check out the classifieds ... someone has (usable ???) parts for sale.
  5. W9GB

    W9GB Ham Member QRZ Page

    CRYSTAL and CERAMIC microphone elements (transducers) were most popular from 1930s to 1960s. Dynamic & Elecret microphone elements replaced them.

    Crystal microphones used potassium sodium tartrate (Rochelle Salt, Seignette's Salt, E337),
    where the crystals are PiezoElectric. HOWEVER, those Rochelle Crystals Breakdown (Dead) with Heat, Shock or Moisture (Rochelle Crystals are Hydroscopic — absorbs water).
    Main Reason they were Replaced.
    1.) CRYSTAL and CERAMIC microphone elements (transducers) are NO Longer Manufactured.
    American mfg. ended at 2000 (reason why Astatic stopped D-104 production & spare parts)
    Kobitone (Japan) stopped crystal/ceramic replacement production after the 2011 Earthquake/Tsunami (lives lost, facilities gone).

    2.) The Blues Harmonica Musicians have bought old microphones, to strip Good Elements.
    That demand has driven prices HIGHER over the past decade.
    In the UK, SHOP at your Amateur Radio Dealer (they will handle Import issues)
    Currently out-of-stock of Heil HC 5.1

    As noted by Steve, WB2WIK … Heil Sound Retro-Fit Kit is EASY for Novices/Newcomers.
    All Parts Provided
    HC 5.1 Retro Conversion Kit … $69.00 USD
    DX Engineering (they do ship global)

    ASTATIC D-104 Microphones
    Catalog (29 pages)

    Schematics (DESK STANDS)
    Last edited: Aug 14, 2021


    Hello all,

    Thank you very much for all your respective suggestions and pieces of advice - very much appreciated. I think I will try to source a seller of the Heil Ham Radio kit as suggested/recommended but keep an eye on in a case of a restock.

    Thanks again and 73s.

Share This Page