Kiwa High Performance MW Air-Core Loop Antenna Repair

Discussion in 'Wireless & RF Design' started by wpri268, Aug 4, 2014.

  1. wpri268

    Thread Starter New Member

    Feb 18, 2012
    22
    0
    Hi. My antenna wasnt working after taking it out of storage for a couple of years. Kiwa no longer manufactures this antenna and consequently has ignored my requests for help or information on diagnosing the problem. Is there anyone out there having experience with fixing these expensive antennas?

    Basically the problem is that it will not tune any frequency, and therefore will not null.

    So far I have examined some of the obvious simple things. The power supply is good from the AC adapter to the output of the regulator. Continuity of the cable between the ctrl box and the preamp is good. I cant find any output signal either at the preamp output or the SO239 connectors with a scope.
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    have you put a signal into the loop? those are amplified recieve antennas and have no output till tuned to a station.
     
  3. wpri268

    Thread Starter New Member

    Feb 18, 2012
    22
    0
    As far as an input goes there is a 10W travelers info station that is about 100ft from my shack. It wont even peak on that signal.

    I've been studying the schematic wondering what would cause the antenna to die while stored in my basement. One thing that caught my eye was a series string of pots- fine tune, main tune, and frequency calibration. While it was alive the main and fine tune pots got lots of use. The cal pot, internal to the control box, would have been factory set and left untouched until now. Maybe that pot is out of adjustment preventing the antenna from tuning anything. That is the next thing I will check out.

    I think I know why Kiwa stopped making this antenna and it has nothing to do with the availability of PVC. A couple of the main amplifier transistors are either obsolete or just difficult to find and are expensive- LS5912. Hopefully neither transistor needs to be replaced otherwise I will just have an expensive paper weight.
     
  4. wpri268

    Thread Starter New Member

    Feb 18, 2012
    22
    0
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