TH-D74 Antenna Connector Broken - Order Parts or Send it In?

Discussion in 'Radio Circuits, Repair & Performance' started by W6EDT, May 2, 2019.

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  1. W6EDT

    W6EDT Ham Member QRZ Page

    I have a Kenwood TH-D74A that has a damaged antenna connector. The SMA Female broke off flush with the white plastic insulator. There are still some threads below that point, so I removed the rubber gasket and reconnected the HT-224 antenna.

    Obviously this is only a short term solution and I need to repair the existing connector, order a replacement part or send it back to Kenwood for repair. I have not opened the radio yet and was looking for information from anyone who may have done this repair themselves. I can do SMT soldering and have some hot air tools as well as the usual soldering station.

    One thing I would like to point out is that the broken piece of the connector which was left inside the HT-224 was flush with the bottom thread on the antenna, leading me to believe that the antenna was not fully engaged on the threads of the SMA connector. This caused excessive stress and it broke when bumped, The rubber washer supplied with the HT-224 is probably what prevented full engagement, as I frequently check the antenna to ensure it is tight.

    Any ideas or experience with repairing this radio would be greatly appreciated,

    Dale Tyler (W6EDT)
  2. W9KCM

    W9KCM XML Subscriber QRZ Page

    I just had a similar incident. The antenna connector is broken. Did you find an easy solution?
    Chuck W9KCM
  3. W6EDT

    W6EDT Ham Member QRZ Page

    Hi Chuck,

    I visited the west coast Kenwood "repair" facility. They wanted $35 and 5 days just to look at the TH-D74. I did not get a good feeling that they had any on site repair techs and think they probably farm out repairs to whoever is handy.

    Because of a lack of competent repair options locally, I ordered the part and will install it myself. Will post again when I complete the fix. The part was only $7.50, so I bought 2 and also the front plastic display cover, which seems easily damaged.

    Dale (W6EDT)
  4. W6EDT

    W6EDT Ham Member QRZ Page

  5. W6EDT

    W6EDT Ham Member QRZ Page

    Updating my own post. This is a *very* easy repair. Almost anyone with basic tools and some mechanical proficciency can fix a broken or cross threaded SMA connector. The new connector is about $7.50 from Pacparts.

    Essentially, the repair procedure is:
    - Remove the antenna, encoder and volume knows (these just pull off).
    - Unscrew the nuts holding the encoder and sma connector. I used needle nose pliers.
    - Pull up on the top cover
    - Remove the rubber gasket
    - Remove the two Phillips screws holding the SMA connector
    - Pull up gently but firmly on the threaded portion of the SMA connector - it will slide off the inner white part of the connector.
    - Separate the threaded part of the SMA connector from the center portion of the replacement SMA connector. You will not need the center part (white insulator and center conductor).
    - Install the new threaded SMA connector over the white insulator on the radio, the the 2 Phillips screws.
    - Reverse the remaining steps. Do *not* over tighten the nuts holding the encoder and SMA to the top cover,
    Total time 10 minutes.

    I will try to attach pictures of the steps, but the description should be helpful, even without the pictures. The surprising thing for me was that the outer threaded part slipped off the inner insulator. I was expecting to have to unsolder the center connector, but was happy that was not required. Of course, ith the center contact is damaged, then the repair is more extensive.

    I also removed R671 (wideband TX) - but that is described well by others. The resistor is quite small - 0201, I think.

    Good Luck!
    Dale (W6EDT)

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