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Mosfet Conversion on a Connex EPT360014B

Discussion in 'CB Radio Modifications' started by Low_Boy, May 17, 2018.

  1. Low_Boy

    Low_Boy Well-Known Member

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    The last of my parts showed up on a slow boat from china and I finished the duel mosfet IRF520 mod.
    http://www.cbtricks.com/miscellaneous/fet_papers/mosfet_conv/graphics/3600xxx_am_fm_mosfet.pdf
    On TR43 and TR44 adjusting VR 10 and 11, I can only get less than 1V on the gate. I just rechecked everything and I did not miss anything. Has anyone tried this mod? Am I missing something or are the directions I am using missing something?


     

  2. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Remember the diodes are different the banded side goes to the left - looking from front to back rear panel and are you using Zeners too?

    94VHPZENERD89D90.jpg

    Or more like the AN1230 series with 1N4148s and resistors?

    Regards!
    :+> Andy <+:
     
    #2 Handy Andy, May 17, 2018
    Last edited: May 17, 2018
  3. Low_Boy

    Low_Boy Well-Known Member

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    NOT home yet but I have the diodes in like the picture and the diodes they call for. I can tell you the exact diode when I get home.Any other ideas?
     
  4. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    IF you're only getting 1 volts to adjust max, then it sounds like a resistor in your divider network between either driver or final is still in - the 1969 ones (Bipolars) used like 47 ohm or so - which you may need to review the jumpers that send RF over FROM Driver TO Finals.

    Tinytraces.jpg

    Since you're doing the "dual-ly" there may be a jumper or trace you left in there connected...they are tiny...

    Click Here to See how Connex Does it


    Hope this helps!
    Regards!
    Drive Safe
    :+> Andy <+:
     
  5. loosecannon

    loosecannon Sr. Member

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    if this is a single final to dual final type of mod, there is a jumper that needs to be added, but isn't in any of the instructions i've seen. JP91? can't remember.
    LC
     
  6. Low_Boy

    Low_Boy Well-Known Member

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    Yesterday was another long day. Didn't get a chance to look at the radio that much. But they're calling for rain this weekend so I don't have to worry about doing yard work ,so I could do radio work instead. I will be at it tonight and tomorrow. I was kind of thinking the exact same thing I left something in or forgot a
    jumper. If there's a jumper they didn't mention that's supposed to be in there that's the one I forgot. Only had a quick chance to look at it with a magnifier while eating dinner .Thanks for the help
     
  7. Low_Boy

    Low_Boy Well-Known Member

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    Thanks guys. Wow I must be brain dead. I was half sleeping when I did the adjustment. Bias is correct.

    PART 2.
    I was excited about trying this mod. My plan was to first do the final and driver. After all was working correctly I was going to slip in the second final. and make it dual irf520 finals with a 520 driver.
    I do not think I will put in the second final and will put the radio back to stock. I am getting 15W PEP on low power and 18W PEP on high power. Very disappointed.

    If anyone has tried this before I would love to hear your numbers.
    Thanks.
     

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