D-104 with TS-520s

Discussion in 'Microphones, Speakers & Audio Processing' started by KI4FMA, Dec 4, 2015.

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  1. KI4FMA

    KI4FMA Ham Member QRZ Page

    I have a TS-520S and D-104 mic that I bought several years ago. I rewired the plug on the D-104 and it works like a champ. The only problem is that it only works in VOX mode. If I lock the key down and switch VOX on I can transmit. However, turning VOX off and keying the mic gets me nothing. I have scoured the web for a solution and have not found anything. Could anyone give me a clue as to what is going on and how to fix it?
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Sounds like you didn't wire up the PTT switch to the rig, or didn't wire it properly.

    On the TS-520S, the mike "hot" line (white from D-104 UG stand) is pin 1, and if the rig modulates, you've got that connected properly. Pin 4 is ground, which connects to the shield from the Astatic UG stand cable, and it sounds like you have that connected properly also.

    You must also wire up pins 2 and 3 of the TS-520S mike plug, using the red wire from the Astatic UG stand and the same ground as the mike uses.

    If you have a later model stand like the preamplified UG-9, that cable has more wires. You have to find the one that works the PTT, and make sure it's connected to the Kenwood mike plug.
  3. W9GB

    W9GB Ham Member QRZ Page

    Jason -

    ASTATIC Microphone Stand --- Schematic Diagrams
    Astatic manufactured the D-104 from 1930s to 2000. 7 decades of 20th century.
    Changes in design (stand types) occurred when solid-state transceivers (Lo-Z input)
    replaced the early (1930-1969) vacuum tube radio designs (Hi-Z input)


    KNOW which D-104 microphone stand that you are using.
    The schematic diagrams (above) should clarify -- for proper wiring.

    This is the Astatic G-Stand (1930-1970) Schematic Diagram
    Note that it has a SIMPLE cable (2-conductor plus shield) and NO electronics in base.
    This was the standard Hi-Impedance (Hi-Z) design for vacuum tube radios,
    using tbe original Ceramic or Crystal microphone element (~ 50K ohms Z)

    Last edited: Dec 4, 2015
  4. KI4FMA

    KI4FMA Ham Member QRZ Page

    I will try to take a closer look at it following your instructions over the weekend.

    As far as the stand mine is the T-UG8. I have wondered if the one I have is a true Astatic due to the fact that there are no markings on the mic, nothing that says Astatic. However, the schematic on the inside of the base plate is an exact match for the T-UG8. I am not sure if there were ever any replicas of the D-104 made by other companies.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The D-104 is the round microphone "head." The stands were always sold separately, and a lot of times the "push to talk" desk stands were not used. D-104s were used on booms, on simple Atlas desk stands without a switch, and lots of ways.
  6. W9GB

    W9GB Ham Member QRZ Page

    It likely an Astatic stand. As Steve, WB2WIK noted -- the stands and microphone heads were sold separately by Astatic. During the 1970s, CB Craze, the D-104 "lollipop" microphone head was mated with a specific stand (retail box set) for the CB stores and amateur radio dealers.

    Astatic sold their desk stands to other manufacturers (OEM), such as Dukane --
    which was based in St. Charles, IL.

    The Dukane 7C40 microphone desk stand (1970s) is the Astatic "G-stand" with the PTT bar.
    HOWEVER, Dukane used that desk stand for DYNAMIC (Low-Z) microphone heads.
    Last edited: Dec 5, 2015
  7. KI4FMA

    KI4FMA Ham Member QRZ Page

    So I played around with the d104 last night and here is what I have. I have confirmed that it works consistently when keyed up in vox mode. I took the radio out of vox mode and tried to key up. There were a couple of times that it keyed up for a second and then unkeyed even though I still had the bar pressed. That would indicate to me that there is a problem with the ptt switch or at least that circuit if it were not for the fact that it works consistently in vox mode. As far as the wiring I found the following on line:

    The only problem is that mine does not have a blue wire. I have white (insulation is actually clear), red, back, and shield. I have the black wire on pin3. Could this be the problem?
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Go back and re-read post number 2, above.

    For PTT to work you need to connect wires to both pins 3 and 4. The red wire closes to ground when you press the PTT switch on the mike stand.

    Use a simple Ohmmeter to confirm. Unless you have both pins 3 and 4 connected to a switch closure, the PTT won't work.
  9. W9GB

    W9GB Ham Member QRZ Page

    Kenwood Hybrid Transceiver Instruction and Service Manuals (FREE)

    Kenwood TS-520S Manual
    PAGE 7, Figure 2 (Assure you are looking at connector numbering correctly)

    Pin 1 - MIC Audio + (HOT)
    Pin 2 - PTT - (Common)
    Pin 3 - PTT +
    Pin 4 - MIC Audio Shield (GND)
    Astatic T-UG8 Schematic Diagram (FACTORY)
    The T-UG-8 microphone stand has a 3-conductor cord:
    + Microphone Audio (WHITE Wire and SHIELD, surrounding the White wire).
    + Switching Conductors (BLACK and RED unshielded wires, sometimes twisted).
    Heil Sound's -- HEIL Wire is virtually identical to this construction and wire color.

    STEP 1 -- Confirm that your Astatic Stand (base) is wired as shown in the schematic.
    This requires Visual Skills (Hand/Eye Ccordibation), Time and Patience.
    This is a Required Inspection Step for "Used" Astatic Mic Stands -- due to large number hacks/mods.
    Some of these changes are outlined on pages 32-35 of Astatic instructions.
    Correct any earlier owner modifications (return to Factory wiring, per schematic)

    STEP 2 - Again, LOOK at Schematic Diagram (above)
    The MAKE-BREAK Section is the Mast Switch (Push To Talk) on the T-UG6 Stand ---
    This is a simple Double Pole, Double Throw (DPDT) switch, on-off-(on)
    The specific contacts of interest for PTT operation are at the first pole:
    "A" (PTT Common) and "C" (PTT +).
    The Electronic/Relay Switch (E/R) must be in the RELAY ("R") position.

    STEP 3 - When possible, it is preferred to ISOLATE the PTT switching function from the
    Microphone Audio lines -- cleaner audio.
    The Kenwood TS-520S 4-pin circular MIC connector (front panel) permits this wiring approach.

    Kenwood TS-520S MIC Connector : Astatic T-UG8 stand mic cord (wire color).

    Pin 1 - MIC Audio (+) : WHITE
    Pin 2 - PTT (Common, GND) : BLACK, switch must be set to Relay
    Pin 3 - PTT (+) : RED
    Pin 4 - MIC Audio (-), Shield : SHIELD
    Last edited: Dec 5, 2015
  10. KI4FMA

    KI4FMA Ham Member QRZ Page

    When I had it wired as described below it was keyed when the key was (should have been) open. Upon further investigation I found that one of the reeds on the switch was bent so that it was always in contact with the one next to it. I have corrected that. Now that is corrected the wiring you described will probably be correct. However, I found that one of the wires (red one) in the cord has a break somewhere. My next step is to see if cutting back the cable will allow me to get continuity, otherwise will have to replace that cable. Once that is done I can verify the wiring of the plug. Thanks for the help.


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