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TUG-8, 10-DA head on Icom IC 740

Discussion in 'Microphones, Speakers & Audio Processing' started by W4MPT, Apr 27, 2012.

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  1. W4MPT

    W4MPT Ham Member QRZ Page

    Recently purchased a 10-da (dynamic) head in good condition to use with my Icom 740. I have been using the old familiar D-104 (xtal) head. No more than the usual troubles so far. Now, I have some concerns, that needs to be allayed. Is there anything that I will need to do to the tug-8 stand or the radio? Whoever put the mic plug on the radio broke off the unused pins. The stand is from 8/75, if the date has any bearing on the circuit.
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

  3. W9GB

    W9GB Ham Member QRZ Page

    The Icom IC-740 uses the common 8-pin circular "Foster" connector, these are readily available from multiple sources: amateur radio retail stores, like HRO-Atlanta, Heil Sound; Digi-Key; Mouser; eBay, countless Internet stores.

    IF the Astatic T-UG8 stand plug, at top of tower, is damaged --
    replacement parts are available from Astatic restorers, such as:
    RB Micro
  4. W4MPT

    W4MPT Ham Member QRZ Page

    Thanks for the info. The mic works (as well as a d104 works with an IC740). I am replacing the d104 head with a 10-da super sideband head, which is a dynamic element. What it really is, is that I'm concerned about the need to decouple the 8v phantom power than the stock mic needs from causing harm to the tug-8 stand and/or the 10-da head, or the radio or all of the above. As it is, the setup with the d-104 works. I don't want to assume that it will continue to work with the dynamic head.

    W9GB- What had prompted my concern was your reply in this thread:
    I have a 1uF tantalum cap on hand, but I'm not sure if it is polarized. Now for the (probably) dumb question of the day....where does the cap go? I must confess my ignorance. Is it inline with pin 1 (which is the white wire) or across pin 1 and pin 7 (braid).

    Thanks to all so far.
  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    You shouldn't even need the isolating capacitor with the T-UG8. The T-UG8 preamplifier has its own isolation capacitor between the level control and the (white wire) output line. Adding a 1uF non-polar cap couldn't hurt, but I'm not sure it would be needed. It would go in line with the white wire, not across pins 1 and 7!
  6. W9GB

    W9GB Ham Member QRZ Page

    Chris -

    This is covered in Bob Heil's All Things Icom, scroll to bottom of this page.

    As Steve, WIK has already noted, IF you have the Aststic T-UG8 base, with pre-amp still
    properly installed in the base -- then the DC blocking capacitor is not required.
    Last edited: Apr 28, 2012
  7. W4MPT

    W4MPT Ham Member QRZ Page

    Ok, things are much clearer now. Many thanks to both of you. It is a T-UG8 base, functioning as it should. Too little knowledge on my part, leading to much confusion. Thanks again for the info.
  8. W7TGT

    W7TGT Ham Member QRZ Page

    You will like the sound of the 10DA head compared to the D104. It has a much mellower sound on SSB. The D104 punches out on AM but, it has too much treble for SSB. If you don't want to mess with it, send it to me. hahaha. I use mine on a IC-718 and get good reports.
  9. W4MPT

    W4MPT Ham Member QRZ Page

    Bingo! That was the whole point of the project. Once I get the impedance matched with the radio, things should be good. This radio doesn't even have AM.
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