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RM Station 550

Discussion in 'Amplifiers' started by redlght, Dec 17, 2016.

  1. redlght

    redlght Active Member

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    I have an RM station 550 no KLV on it that sounds horrible on sideband but clean on AM i tried this fix but can not seem to make it sound good on SSB any ideas? This amp does not have R29 and 30 side by side. here is a photo of the amp and 2 scope snaps of modulation with the amp off and on. Any help would great. Thanks


     

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    #1 redlght, Dec 17, 2016
    Last edited: Dec 17, 2016

  2. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    #2 Tallman, Dec 17, 2016
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  3. redlght

    redlght Active Member

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    Mine is not a KLV it is an RM Station 550 It uses two 2SC1407's the resistor is left side by the diode and transistor. if you bring up image then right click view image it will enlarge. here is a pic of the klv550 board lay out R20 and 30 are circled in red
     

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    #3 redlght, Dec 17, 2016
    Last edited: Dec 17, 2016
  4. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Don't click on the thumbnail. Click on the file name and it should appear quite large or you can save it and use an image editor to enlarge it.
     
    Tallman likes this.
  5. redlght

    redlght Active Member

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    Good tip Cap
     
  6. redlght

    redlght Active Member

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    Be nice if they gave you voltages on the schematic such as TR9 I was trying to follow Bob's bias fix but mine is a bit different
     
    #6 redlght, Dec 17, 2016
    Last edited: Dec 17, 2016
  7. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    The schematics I have are an older or perhaps newer than the board you have shown.
    I do see lots of solder problems on the board. There is a TO-220 transistor that sets up the bias for the final transistors that appears to be unsoldered. If you closely inspect the board you will see multiple solder joints that don't have solder on them.
    Also the missing resistors supply voltage and current to set the bias up for class AB operation. You might need to go to the RMItaly site and find the proper schematic for your unit. The KLV unit I have is newer than yours so there are differences between the two. If you need more help I'll jump in later, but I'm sure you will get it running again.
     
  8. redlght

    redlght Active Member

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    I can not find a schematic for it. I have soldered up those joints after the pic was taken i replaced all of the transistors in it. I have hit the wall on this one
     
  9. sp5it

    sp5it Master of puppets

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  10. redlght

    redlght Active Member

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    I was trying this mod but mine is a bit different did not want to make a mistake. Also the 4 pin jumper i am guessing it goes on the top 2 pins.
     
    #10 redlght, Dec 17, 2016
    Last edited: Dec 17, 2016
  11. sp5it

    sp5it Master of puppets

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    Draw it's schematic, than we can help you.
    Mike
     
  12. redlght

    redlght Active Member

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    That would tough with bad eyes guess it is a paper weight
     
  13. autotuner

    autotuner Supporting Member

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    Might be a silly question but are you sure your power supply is up to the task?
     
  14. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    The link to the schematic is good for your unit as well. Does your HamStation have a DC power supply for the radio?
    RM Italy changed board layouts all of the time, once they have the basic design they don't really change much other than the position of the parts. And very rarely do they change the reference designators.
     
  15. redlght

    redlght Active Member

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    Yes it has the built in power supply it is rebuilt the amp does 300 watts but nasty ssb audio \> what are your4 pin jumper settings?
     

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