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Thread: RM KL 500/24 LINEAR IS KAPPUTT

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  1. #1
    Join Date
    Feb 2009
    Location
    wednesbury
    Posts
    29

    Default RM KL 500/24 LINEAR IS KAPPUTT

    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 by M0CRU; 02-21-2009 at 10:31 AM.

  2. #2
    Join Date
    May 2005
    Location
    Holland JO23TA
    Posts
    1,294

    Default

    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.

    http://home.hetnet.nl/~l.van.lelieveld/

    Here the changed version of the KL 500 to make a decent amp from it with switchable lpf filtering, better bias etc.
    Licensed since 1977

  3. #3
    Join Date
    Nov 2009
    Location
    Ruislip London
    Posts
    94

    Default

    Quote Originally Posted by M0CRU View Post
    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??
    Hi did you ever get a little amp for the qrp rig
    Damian

  4. #4
    Join Date
    Oct 2003
    Location
    Middle Georgia USA
    Posts
    7,722

    Default

    Quote Originally Posted by M0CRU View Post
    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??

    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.
    http://www.w8ji.com/rm_hla-150_test.htm


    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. #5
    Join Date
    Jul 2001
    Posts
    21,474

    Default

    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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