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

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

ad: L-HROutlet
ad: l-rl
ad: abrind-2
ad: QSOToday-1
ad: L-MFJ
ad: Subscribe
ad: Left-2
ad: Left-3
  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 Premium 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

    Step1_RemoveEncode-AntennaNuts.jpg Step2_NutsRemoved.jpg Step3_SlideTopUpandOff.jpg Step4_TopRemoved.jpg Step5_RemoveRubberGasket.jpg Step6_Unscrew2PhillipsonSMA-PullUpThreadedPart.jpg Step6A_NewSMAConnectorSeperated.jpg Step7_InstallNewThreadedSMA-ReinstallPhillipsScrews.jpg Step1_RemoveEncode-AntennaNuts.jpg
    W1TRY and AI3V like this.
  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)
    W1TRY and KJ7NUX like this.
  6. VA2XMP

    VA2XMP Ham Member QRZ Page

    I almost have the same issue except my volume/encodet knob bent a bit because the radio felt.... I have no idea how to remove the part beside the video from Don. I know I have to dismount the radio but how to remove the part and where to get the new part.

    Stephane VA2XMP

  7. W1VT

    W1VT Ham Member QRZ Page

    A destuffing tool is used to remove the large nut holding the SMA connector down. Yes, "destuffing" is the name to use on Amazon or ebay if you want to buy the proper tool.

    Zak W1VT
    W1TRY likes this.
  8. VA2XMP

    VA2XMP Ham Member QRZ Page

    Thanks... A friend was able to to use visegrip tool and replace the pin. Saved 185$ (shipping and handring plus part) Still ordered a part in case!!!
  9. KJ7NUX

    KJ7NUX Ham Member QRZ Page

    I want to thank you for this post. I just noticed a crack on my front cabinet, which some refer to as the top plate but is actually on the back of the unit. I freaked, as this was my first radio purchase (new technician). I immediately ordered the replacement and started looking for "how-to" videos. Your pictures and instructions have really eased my anxiety. I look forward to starting my repair when the part arrives.

    I have always kept the radio in a case and I have never had a drop on it. I wonder if the crack was there since purchase. I only noticed the crack because I needed to change the battery and the light was just right...

    Thanks again!

    KJ7NUX or Crittenden

  10. W1TRY

    W1TRY XML Subscriber QRZ Page

    I can't see how this would work, Zak...

Share This Page