Why would a DECT Panasonic cordless phone keep losing the wirelesslink?

Discussion in 'Electronic Repair' started by Danny D'Amico, Jan 7, 2014.

  1. Any idea why fully-charged DECT Panasonic cordless phones would
    keep losing their wireless link lately?
    http://farm4.staticflickr.com/3720/11812145904_ab84d957e3_o.gif

    They're not at all far (fifteen feet) from the base and, this
    loss of signal only started happening about a year ago (the phone
    is probably about three or four years old).

    So, something clearly aged (but the batteries show as fully charged
    and I've changed them between handsets anyway).

    The error I keep getting (on multiple handsets) is:
    No Link. Reconnect base AC adapter.

    This happens after, say, a few minutes of talking time, but, it's
    erratic. Sometimes I can be on the line for an hour before it
    happens; other times it happens within five minutes.

    What frustrates me is the lack of debugging techniques.

    Reconnecting the phone to the charger doesn't change anything;
    nor does placing each of the handsets back into the mother phone
    to reinitialize them.

    Here's the DECT Panasonic KX-TG6441 phone & handsets:
    http://farm4.staticflickr.com/3779/11811980883_f540a29bee_o.gif

    Here's the model number plate:
    http://farm6.staticflickr.com/5539/11812098283_c1f2dc22f0_o.gif

    Googling for that error message, I see it's pretty common; but
    I already tried the little that Panasonic suggests:
    http://eng-na.faq.panasonic.com/app...base.-reconnect-ac-adaptor.-what-should-i-do?

    The outlet is working fine; the phone works fine from the base;
    it's just the handsets that keep losing their wireless connection.

    Anyone else resolve this problem before?
    Any debugging hints?
     
    Danny D'Amico, Jan 7, 2014
    #1
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  2. Danny D'Amico

    mike Guest

    Sounds like interference.

    I recently switched to a high-power router and Wi-Max wireless internet.
    One or both drove my 2.4GHZ wireless phone crazy. Hardly worked at all,
    even up close.
    I powered up the spectrum analyzer. Yep they were right on top of
    one another.
    I switched to a DECT phone, which, as I recall, works on different
    frequencies.
    Problem got a lot better. I still can't stand too close to the router.
     
    mike, Jan 7, 2014
    #2
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  3. Danny D'Amico, Jan 7, 2014
    #3
  4. Hi Jeff,

    Googling, it says the error indicates the base station loses its
    power, but, that's just not happening, at least not from a loose power
    cord.

    The reason I know that's not happening, other than it's not, is that
    not all of the handsets fail at any one time. Only one handset fails
    at a time.

    So, if it was the base failing (which is what the error indicates),
    then all the handsets should fail simultaneously, I would think.
     
    Danny D'Amico, Jan 7, 2014
    #4
  5. As someone suggested, I guess it could be my 2.4GHz WiFi antenna
    that is causing problems; but why would that be intermittent?
    This is likely. The error indicates a lack of power at the base,
    but, there isn't any overt lack of power at the base.
    This makes a lot of sense - and it's a good idea, especially since the
    error indicates a lack of power at the base.

    I'll try that and re-test & report back.
     
    Danny D'Amico, Jan 7, 2014
    #5
  6. It could be. There's a lot of WiFi floating around my house these days.
    I had to look up WiMax:
    http://en.wikipedia.org/wiki/WiMAX
    I hadn't thought of aiming my spectrum analyzer inside (mine is pointed
    outside). What I may try is setting up a spectrum analysis where I
    run a 1000 frames without any devices plugged in, and then another
    1000 frames with all my WiFi devices plugged in to see if there is a
    big difference.
    I don't know what frequency DECT works on, but, two of my four
    phone bases are DECT.
     
    Danny D'Amico, Jan 7, 2014
    #6
  7. Danny D'Amico

    Tony Hwang Guest

    Hi
    One base and many handsets? Then logic tells me radio in the base unit
    is suspect. Or turn all handsets but one and try. By any chance checked
    the wall wart for the base unit? We have multi handsets but they are
    divided between two different base units. If some thing goes wrong easy
    to trouble-shoot
     
    Tony Hwang, Jan 7, 2014
    #7
  8. Danny D'Amico, Jan 7, 2014
    #8
  9. There are three kinds of interference that can happen in this case.

    The first is direct interference, where your WiFi unit operates on 2.4gHz
    and your cordless phone also operates on 2.4gHz. The old 2.4gHz phones
    did not listen for activity on a channel before transmitting on it, and
    often would wipe out Wifi.

    The newer DCT phones listen, but there is only so many channels and eventually
    they overlap.

    Since 2.4gHz is 1/2 of 5.8 gHz, the second harmonic of WiFi can interfere
    directly with 5.8gHz phones and so on.

    The second is intermodulation, where two signals combine and the difference
    or sum causes interference. Not likey in this case.

    The third is desensitization, where a strong signal on a relatively near
    frequency overloads the receiver in a device. So a WifI router can cause
    DECT phones to stop receiving, even though WiFi is 2.4gHz and DECT is 1.7gHz.

    That's why you can't talk on the DECT phone near your WiFi device.

    It's very likely that the OP is experienceing desensitazation or direct
    interfernce.

    Another thing they can try is to move the base station. Especially if it
    is sitting next to another wireless device.

    Geoff.
     
    Geoffrey S. Mendelson, Jan 7, 2014
    #9
  10. It may not be YOUR WiFi that is causing it. Unless you live in a single
    family house about 1/2 km from anyone else and a road, you could have
    problems with interference from other WiFi devices, cordless phones,
    cell phones, and so on.

    I live in a steel and poured concrete building, and away from the center of
    it (I'm on a middle floor), say my bedroom, I can only "hear" my Wifi.
    In my living room which is in the center, I can "hear" 8 unprotected
    WiFi networks, and a few protected ones. It's a miracle I can use my
    WiFi there.

    Geoff.
     
    Geoffrey S. Mendelson, Jan 7, 2014
    #10
  11. Danny D'Amico

    Phil Allison Guest

    "Geoffrey S. Mendelson"

    ** That some new kind of math ???

    ROTFL



    .... Phil
     
    Phil Allison, Jan 7, 2014
    #11
  12. You're spending too much time analyzing the problem, and not enough time
    testing.

    Why hasn't someone suggested changing the WiFi channel? That's a great place
    to start testing.
     
    William Sommerwerck, Jan 7, 2014
    #12
  13. Any idea why fully-charged DECT Panasonic cordless phones would

    *The last time my Panasonic phone did that, I replaced the batteries with
    new ones. Problem went away. If yours are four years old I would think
    that it is time for a battery replacement. Home Depot has them and I think
    Wal-Mart does also.
     
    John Grabowski, Jan 7, 2014
    #13
  14. Danny D'Amico

    Jeff Urban Guest

    If they're 2.4 Ghz, wifi could be interfering too much.
     
    Jeff Urban, Jan 7, 2014
    #14
  15. Percival P. Cassidy, Jan 7, 2014
    #15
  16. DECT phones are on 1.9gHz (1.7 in Europe), DCT phones at 2.4gHz.

    They are similar, and of course, incompatible.

    Geoff.
     
    Geoffrey S. Mendelson, Jan 7, 2014
    #16
  17. Danny D'Amico

    Oren Guest

    I was thinking about it :)
    Even suggested when installing a home router. Change the channel if
    there are problems.
     
    Oren, Jan 7, 2014
    #17
  18. This is very useful information, an applicable to the WiFi group as well.

    My DECT Panasonic KX-TG6441 phones & handsets apparently operate at
    1.9 GHz, according to page 6 of this PDF:
    http://service.us.panasonic.com/OPERMANPDF/KXTG6431-MUL.PDF
    "The product operates in the frequency range of 1.92 GHz to 1.93 GHz,
    and the RF transmission power is 115 mW (max.)"
     
    Danny D'Amico, Jan 8, 2014
    #18
  19. Danny D'Amico, Jan 8, 2014
    #19
  20. This is a good point!
     
    Danny D'Amico, Jan 8, 2014
    #20
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