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Discussion in 'General Technical Questions and Answers' started by M0CRU, Feb 21, 2009.

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  1. M0CRU

    M0CRU Ham Member QRZ Page

    when the linear is inline but switched off, my antenna is recieving 7W (icom 703 qrp) but when i switch it ON, no power at all is going into my antenna ZILCH, i find it hard to believe that BOTH "sd1407" transistors are blown. plus where is the icoms 7w dissapearing to? any thoughts anyone??
    Last edited: Feb 21, 2009
  2. PA5COR

    PA5COR Ham Member QRZ Page

    It's a crappy broadbanded CB amplifier.
    Rebuild one, better bias, good lpf, for use on 10 meters in the car.

    Look for faults at the input attenuator, maybe a resistor blew up for too much input?
    Check the pcb for obvious visible faults, burned components, loose connections.
    The schematic diagram is on the site of RM.

    Here the changed version of the KL 500 to make a decent amp from it with switchable lpf filtering, better bias etc.
  3. G4LHT

    G4LHT Ham Member QRZ Page

    Hi did you ever get a little amp for the qrp rig
  4. W8JI

    W8JI Ham Member QRZ Page

    The RM Italy amps are sold on "power lies", and the one you have is unsuitable for amateur use. It is a cheap CB amplifier, and a dirty one with no filtering.

    RM Italy grossly overrates the output power of all their amplifiers.

    You could have done one of two things.... trying to run the power they claim you may have overheated and unsoldered or ruined the R12 resistor (if it is installed) that is in series with the drive line to the PA input, or you blew the output transistors.

    You really need a different amplifier for amateur use!!!

    You can see a HLA 150 test here.

    The HLA 150 is marginally suitable for amateur use at 100 watts PEP of power, although they rate it at 300 watts PEP.

    73 Tom
  5. AG3Y

    AG3Y Guest

    Damian, you resurrected a zombie thread, but Tom added some excellent information. But I hope this thread dies a clean, natural death, now. No further good can come from it.

    73, Jim
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