LDG AT200 PRO Tuner problem

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by PA3CVI, Apr 27, 2011.

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  1. PA3CVI

    PA3CVI Ham Member QRZ Page

    My configuration:

    Tranceiver: TS480-HX, max. pwr 200Watt HF.
    Antenna : 6 band Vertical MA6V of Cuscraft

    Approximately 3 weeks operated this Antennatuner to my satisfaction, no problem at all.

    Afterwards (at the same configuratie, same situation, same adjusting, max. 100 Watt HF power) I saw on that the ATU intolerable hot became because these started smell strangely.
    One of the coils becames extremely warm ! Now, I have sent the ATU to the salesman there to be repaired.

    They have tested the ATU with a Dummyload 25-50-75 Ohm (purify Ohm's), but with this measures method they could observe no temperature increase.
    In practice the ATU have been connected to a antenna as inductive or capacitieve load. Perhaps is testing under these conditions the only corrct method?.
    Certified repairing department will do there further research nasty

    My question: what is the reason for overheating and what can do I against ?


  2. KB7FHK

    KB7FHK Premium Subscriber QRZ Page

    run your tuner into a dummy load and see if it gets hot. Your antenna system may be out of the tolerance of the tuner? check for dirty/wet connectors/broken coax? maybe use an antenna analyzer on feed and antenna.

  3. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    I'm with Ace on this one. There are a lot of antennas on the market (no matter the hype, no matter the popularity, no matter what), that in reality, aren't what you might say, are breakfast of champions! Sure, they work, but no one seemingly defines what work means! The MA6V is in that category. Assuming you put it together like MFJ suggested, and you checked the SWR at the resonant points you set it up for, then perhaps the LDG might allow you to QSY from those resonant points at least a few KHz away. If on the other hand you assumed the LDG would handle whatever impedance the antenna threw at you.... you've jumped off the pier!

    This specific antenna presents a rather large amount of common mode current. That is why there is specific instructions included about winding the common mode choke. Even then, there is still quite a bit of CM to deal with. Depending on the length of the coax feeding the antenna, you may, or may not, experience problems. Apparently you are.

    Again, assuming you mounted the antenna like MFJ suggests, you need to measure the input impedance (sans the LDG), to see if it is even close (at the antenna, not at the shack end of the coaxial feed). I'd bet it isn't. In fact, I suspect the resonant points are way off from what they should be.

    It is unfortunate, that today's amateurs have to buy additional hardware (i.e.: MFJ-259B or similar antenna analyzer) to make sure what the manufacturers say in their manuals is correct. Oh! This is yet another case where an SWR bridge is almost worthless.
  4. PA3CVI

    PA3CVI Ham Member QRZ Page

    run your tuner into a dummy load and see if it gets hot.
    Answer: the tuner is still at repairing service for research further.

    Your antenna system may be out of the tolerance of the tuner?
    Answer: No, the SWR are adjusted automatically by the tuner up to 1:1
  5. PA3CVI

    PA3CVI Ham Member QRZ Page

    Thanks Alan, Ace, for your explanations, and I become not lively there of.

    Possibly the vertical antenna are not, in my opinion, the cause of the problem.
    To keep my problem simple, I have been not complete in my description of my antenna equipment.

    To the same ATU, a centre feed dipole antenna has been still linked.
    Also these Antenna give the same problem, the ATU regulate near 1:1, but become are too hot.

    If you want the effort observe my Internet site to visit, http://www.pa3cvi.nl, you get an insight how I worked before I bought the ATU. My homemade ATU' s give, however, a workable situation in combination with both antennae.

    After your enumeration of all plausible facts on ATU and antennae, unfortunately I can do nothing with your information, and it solves my problem unfortunately not.

    Cees, PA3CVI
  6. AD4J

    AD4J Ham Member QRZ Page

    If a coil is getting hot, it is probably because high current is passing through it. If I understand correctly, the tuner used to run cool with both antennas (vertical and open wire fed dipole) and now gets hot with both antennas. Does this happen on all bands or just certain ones?

    Do you use a balun between the open wire feed line to the dipole and the tuner?

    Have you measured the SWR or impedance at the point where the feed line connects to the tuner (NOT between the tuner and rig - I understand that the SWR is 1:1 there)?

    73, Jim AD4J
  7. PA3CVI

    PA3CVI Ham Member QRZ Page

    If I understand correctly, the tuner used to run cool ............
    The first three weeks the tuner worked uncomplicated at both antennas without overheating.

    Does this happen on all bands...............
    It makes no difference in overheating or the vertical, or the dipole has been connected, also the problem is frequency (bands) independent.

    Do you use a balun between.....................
    This tuner has two antenna connections, wich can be selected with a push-button on the frontside.
    And yes, I use a balun 4:1 between the open wire feed line to the dipole and tuner.

    Have you measured the SWR or impedance at the................
    - The tuner himself has a SWR meter, which I had adjusted on 1:1.2. If he value < is; 1:1.2, then again regulates the tuner in.
    - My tranceiver has also overall SWR meter and these give then value to minimum SWR to (one led).

    Later I have removed the cap of the tuner and observed that one of the coils this way became hot, that the coil will sit a little separately.
    The two swr values intolerable going up.

    Cees, PA3CVI
  8. AD4J

    AD4J Ham Member QRZ Page

    Since the tuner heats up on all bands and with either antenna, it sounds like the tuner that has gone bad (despite the dealer's claim to the contrary). Does the dealer have a replacement tuner you can try? Are you temporarily using the manual tuners shown on your web site? If so, are the settings for a match similar to before you got the LDG unit?

    73, Jim AD4J
  9. PA3CVI

    PA3CVI Ham Member QRZ Page

    Well idea Jim, concerning the proposal for a replacing equivalent tuner but I will still waiting for just as if the dealer can solve the problem.
    Yes I'm using now the handtuners for the contesten and dx-activities.
    I'm not sure about the dipole antenna, about the vertical the settings are similar for a match to before.
    I keep you informed of further information.

    73, Cees, PA3CVI
  10. NA0AA

    NA0AA Ham Member QRZ Page

    I've had four LDG tuners and still have three of them [sold one I no longer needed], and I've never seen a problem as you describe, so I suspect you got the rare bad one, I run my AT-200 with a 200 watt radio and have never had a lick of problem with them heating.

    You might have a stuck relay that's causing this to burn up, I doubt it's your antennas causing the problem - even if the feedline was shorted, you would not achieve a workable match and the tuner would tell you.

    So, my Two Cents are on a defective unit, now I have no idea why it failed except to note that most electronic gear fails in the first 90 days if it's a bad component.
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