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MOSFET conversions for upD858 and MB8719 boards

Discussion in 'General CB Services Discussion' started by ExitThirteen, Mar 10, 2011.

  1. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    My first post has the dual conversion MB8719 chassis (Cobra 148GTL, Uniden Grant (XL), Cobra 2000GTL), so check there. I need to do up the PLL 02A Cybernet AM/SSB chassis.... I keep forgetting to post it! :oops:



    ~Cheers~
     

  2. Meglotron

    Meglotron Member

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    good luck finding even one radio on earth that shows 6db for a s unit. after I read an old thread about ham radois being as low as 1 to 2db an s unit ive tested mine with a couple gyus who can ajust there power and its more like double the power for a s unirt
    im bumping this thread because its xlnt information
     
  3. liquidh8

    liquidh8 Active Member

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    Did thes mess up SSB at all? Do you have to re-align the radio for SSB? I am glad I found this thread, thank you!:w00t:

    Maybe we can get a dual mosfet in this, lol

    I have a president 858 chassis, 2 button with the 1307 final doing 22-23 on SSB.
     
  4. Robb

    Robb Yup

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    No; re-alignment is unnecessary when putting in the MOSFET.

    If you have a 1307 final, I wouldn't change a thing.
    If you want more power; then run a 200w amp . . .
     
  5. liquidh8

    liquidh8 Active Member

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    Ok, I do have that final. I have an amp I have to replace the pills in, just curious as to what difference I would get. I'll be saving this info though in ase that final craps out on me. My buddy has the uniden washinton with 8719 pll and the 1969 finals.
     
  6. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    1306 driver and 1307 final combo is just fine if it is working, and I doubt you will ever find those transistor`s any more....rare as hens teeth.

    73
    Jeff
     
  7. jazzsinger

    jazzsinger Bullshit Buster

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    got a couple of those old nec (if they ain't nec they ain't real) hen's teeth here.:D

    if your final craps out replace it with a 2sc2312 or 2sc1969 eleflow transistor. they work well and can be got on e bay cheaply.
     
  8. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    That is E-bay gold right there Jazz.
    Put them up for Auction with words like Vintage, rare, no longer made, new old private stock, stored in a temp controlled, moisture and smoke free environment.
    Take pictures of you removing them from sealed 1 gram zip lock baggies while wearing latex gloves and holding them with a pair of stainless steel forceps, or even better yet, do a you-tube video with music playing in the background like the guys at cobraworxshops.
    Add that they are Original replacements for Vintage, Rare No longer made, collector Radios, and start the bidding at $100.00 each with a $400 reserve.
    e bay is just chock full of guys with $$ signs in there eyes for stuff like that.

    (y)

    73
    Jeff
     
  9. liquidh8

    liquidh8 Active Member

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    Anyone ever try one of those high power mosfets, like you see in the H&Y catalog? That would be something, a 100watt washington, lol!:drool:
     
    Ninetok likes this.
  10. Se7en

    Se7en Well-Known Member

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    HFR-20W (2SC1969) ELEFLOW HF/RF TRANSISTOR....1pc. | eBay
     
  11. liquidh8

    liquidh8 Active Member

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    fwiw, I was bored, and tried it on my president. Checking the voltage at the gate, i get 6.6 vdc, smoked one mosfet. Can't seem to get it lower.
     
  12. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    You using a 56k ohm resistor to the 13.8V on the RF choke? That should put the voltage at 3.65 volts or so. I still have the MOSFET in my President Washington from about a year ago, and it works great.


    Just remember that you have to follow my instructions to the letter for optimum performance. Keep trying, you'll get it. :)


    ~Cheers~
     
  13. Double R

    Double R Member

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    what do you do if ya cant get the en-369fn at radio shack
     
  14. liquidh8

    liquidh8 Active Member

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    Yes, I had to use a different companion part. (i had irf510's and 520's) But, after you get itall in, the resistor and the mosfet, I can't really tune up the tx as the instructions say. When I start to turn the tuning slugs, the voltage at the gate rises. The old VR for the final bias has no effect. So, IOW, I only get about 6 watts out of it with the tuning slugs in almost the stock location, so as to keep the voltage at the gate at 3.65 vdc. If I try and "peak" it like the sock finals, it smokes the mosfet.
     
  15. ExitThirteen

    ExitThirteen Grumpy and Cranky

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    Can you take a picture of the underside of the radio where you have the resistor mounted? Tuning the slugs shouldn't be raising the gate voltage. Mine stayed at 3.65V no matter what I tuned in the radio... I'm wondering if you're pulling voltage off a different source somehow, or you didn't remove a component that cuts off the original biasing circuit. Shoot me a good pic, and I can help troubleshoot.


    ~Cheers~
     

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