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Thread: Issue with Kenwood TM-221A PL tone

  1. #1

    Default Issue with Kenwood TM-221A PL tone

    I have been using my Kenwood TM-221A mobile 2 meter for many months now, and I have not made any mods or adjustments to it. However, it has recently developed a rather peculiar problem.

    When I first use the radio, the PL tone works fine, but after about five or so minutes, the PL-tone fails to work even when the controls of the radio are left untouched. Switching the radio off and on does nothing unless I switch it off and let it rest for several hours. Is there any thing I may have overlooked or is the radio in need of repair? If so, what can be done to remedy the problem?

  2. #2

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    When something works good cold, gets warm and fails, then works again once cooled, I immediately think thermal stress fractures on a solder joint somewhere.

    Although the symptoms are slightly different in the article I found, it mentions a CTCSS related component which is susceptible to thermal stress fractures in solder joints. The linked forum mentions a resistor network (IC4 for smoothing out the square waves) that might need resoldering. See reply #9 in the link below. I imagine a thermal stress fracture could yield countless varieties of ghosts in a radio, start with the hottest thing near the CTCSS circuit.

    https://www.eham.net/ehamforum/smf/i...?topic=79647.0

  3. #3

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    That was my first guess as well, just wanted a second opinion before I took unnecessary action.

    Sadly, I lack the knowledge to actually repair the problem, how much would it cost to pay a good technician to rectify the problem, and is it even worth it for such an old radio?

  4. #4

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    That's a tough question, one that really depends on how much you like the radio. Shop time for radio repair around here is usually around 40 per hour. That radio is going for about 75 USD on Ebay. If I am correct, the repair should take less than an hour.

    You might get lucky and find a local ham willing to dig into the face plate and re-flow some solder joints for free...

    EDIT: another option is to sell the radio (while being honest about the problem in the ad). Someone familiar with that radio might buy it for parts or repair.
    Last edited by brandon lind; Mon 11th Mar 2019 at 17:20.

  5. #5

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    I have decided to simply replace it with a Kennwood TM-261A. Are those any good?

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