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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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    M0GVZ,



    If I was able to get them easily, I'd use the good Eleflow C1969's that Weazle66 sells. Unfortunately, it's not cost effective, as it costs more to ship the final across the pond than it is to actually purchase the final! :LOL:


    I do it for cost effectiveness. Genuine finals are tough to get now in the States, and fakes are running rampant. That's the purpose of creating these mosfet mods.


    ~Cheers~
     

  2. M0GVZ

    M0GVZ Sr. Member

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    Actually it has more than four times the gain of a dipole over real ground.

    If its for parts availability then fair enough. Just seemed a lot of grief for very little increase in power.
     
  3. GnG8d

    GnG8d Well-Known Member

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    :LOL: good one!
     
  4. Heatwave1972

    Heatwave1972 Member

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    Where is L40 Located, The Schamatics don't show L40
     
  5. Robb

    Robb Yup

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    Yes, it should.

    While a Madison is really just a re-badged 148GTL if it has the 8719 pll, the output schematic should be the same. So the MOSFET mod should work. Been there; done that.
     
  6. Heatwave1972

    Heatwave1972 Member

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    Can You ExitThirteen Please Let Me Know Of Mosfets On The Am Side, I Did The Side Band Replacing The Final With IRF530 And Did'nt Have To Put Caps Or Resistors. I Have 50 Watts On Sideband. Now I Like To Find Out The Am Side. The PC-385 Does Not Have The L40 .
     
  7. orbieswar

    orbieswar Member

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    A very interesting thread.. A big thankyou to 13 and all that have contributed.
    But I am curious. This mod is proven for the second generation D858 PLL, But what about older units with the pll in the tin boxes ?. Like P/S SIMBA 2 & CHEETAH 2, or the Courier CENTURION and MIDLAND ?
     
  8. Robb

    Robb Yup

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    IIRC, the AM only radios will have a slighly different approach for the MOSFET conversion since they use class B biasing. The SSB radios with class AB biasing will use the conversion in this thread.

    Perhaps Xit13 has done the AM only conversion too?
     
    #98 Robb, Feb 1, 2015
    Last edited: Feb 1, 2015
    orbieswar likes this.
  9. orbieswar

    orbieswar Member

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    Yes the AM only sets would be different.. I have the Cheetah SSB 2 with the D858. I am not sure as to whether the output stages are the same as the GRANT etc.
    Just thinking there are maybe hundreds of these older classics out there with the earlier UNIDEN SSB chassis and was just wondering if the conversion was the same.
     
  10. Heatwave1972

    Heatwave1972 Member

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    Exit I Did This Mod Already, But I Don't See The Full Side. Just The Single Mod
     
  11. Heatwave1972

    Heatwave1972 Member

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    I Wanted The Dual Conversion
     
  12. mechanic

    mechanic Well-Known Member

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    Is there a conversion like this for the HR2510 / Lincoln?

    TIA es 73 mechanic
     
  13. pede69

    pede69 Member

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    Hey 399...

    What's wrong with the 858's?

    J
     
  14. Onelasttime

    Onelasttime Well-Known Member

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    Why would you want to use Mosfet's when you can still get real 2SC1969's? from RF Parts? I could see if you needed something crazy like 10 matched 1969's or something insane but the price of a single 1969 for a good working vintage chassis especially if it is a SSB rig is cheap. I am 43 years old and I have never blown a final in any radio. In fact I have never blown a single transistor in the rf area or had one go bad. I have had a crystal filter go bad, and a voltage regulator go bad but never a final. So baring use in a tank, light aviation, helicopter or big rig I would suck it up and go with a real 1969.

    The added power of a signle or dueal mosfet compared to a signle or dual 1969 is meaningless and worthless in the real world. If your pandering to watt meter's and looking to maximize your profits I can see it but not for much else. That said I am guessing 99% of people that would sub them would not pass the insane price savings on to their customer most would charge them extra which makes them douche bags in my book given the HUGE price savings. I get the Mosfet's for less than a dollar but pay $16.96 from RF parts for real 2SC1969's!
     
  15. Dave239

    Dave239 Member

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    your missing the point of this thread. Its about the fact that it is possible to do it. I have bought these new transistors and they are sub-standard. So We applaud Exit-thirteen on his work instead of mocking it.
     

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