What's in it?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N9XAW, Jun 8, 2021.

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  1. N9XAW

    N9XAW Ham Member QRZ Page

    I have aTD-90 Tennadyme folded dipole resistor terminated. Recently it quit performing on any band but 40 meters. I contacted Tennadyne for advice. Their only responsw was you have an old antenna and buy a new one. There can't be that much in this antenna. I suspect a balun and a resistor. Anyone had one apart? Can it be brought back to life?
     
  2. K7MEM

    K7MEM Ham Member QRZ Page

    You may be able to bring it back to life, if you can get the parts.

    The first step would be to check all connections. A corroded lug is all that's needed to throw off the antenna. The terminating resistor often uses clips that can get corroded, without readily showing.

    Then I would remove the Balun and check the integrity of the wire/terminator. You should be able to put a ohm meter across the feed point, without the Balun, and read the value of ther terminating resistor. I don't know what value Tennadyne uses, but it should be in the range from 450 to 1,000 Ohms. Maybe even smaller. A small part of the reading will be the resistance of the wire.

    If that all checks out, the only thing left is the Balun. You might have to open up the Balun to check the windings. A shorted/open winding could cause issues. Or, if you have a antenna analyzer, you could attach a load to the Balun and check for a 50 Ohm input. If you make the load the same value as the terminating resistor, you should be able to get a good reading. The Balun should probably be either a 12:1 or 16:1.
     
    N9XAW likes this.
  3. WA7ARK

    WA7ARK Ham Member QRZ Page

    K1LKP likes this.
  4. K1LKP

    K1LKP Platinum Subscriber Platinum Subscriber QRZ Page

    BOB,

    SEND AN EMAIL TO THESE FOLKS AND EXPLAIN THIS ISSUE TO THEM.
    THEY WILL TELL WHAT PRODUCT TO PURCHASE.

    http://www.balundesigns.com/servlet/StoreFront

    THEY MAKE SUPER PRODUCTS.

    THREE CHEERS FOR THE GATOR NAVY.....BRAVO...

    73 ES SMOOTH SAILING
     
  5. N9XAW

    N9XAW Ham Member QRZ Page

    **Excellent** Thank you very much. 73
     
  6. N9XAW

    N9XAW Ham Member QRZ Page

    Armed with your information, I lowered the antenna. It wasn't easy as the pulley apparently would not turn.
    When I finally got it down the problem was immediately seen. The antenna wires had corroded and broke contact with the resistive load section. I removed the connectors, cleaned and put new lugs on the wires (soldered, not just crimped), cleaned the rest of the washers and nuts and replaced them all. The balun section was also corroded but not broken. I replaced the connectors for good measure. Rain put a halt to the progress, but tomorrow I will seal the connections with liquid tape. While it is down I will also replace ropes and raise it up again. Thanks again for your help and encouragement. DE N9XAW 73
     
    K2CD likes this.

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