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98VHP w/ 63FFC4 bottom

Discussion in 'CB Radio Modifications' started by TheRealPorkchop, Oct 11, 2017.

  1. TheRealPorkchop

    TheRealPorkchop
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    OK, here's one for ya to think over...

    I've done this 3 times now, the results are often exactly the same. Word of advice, don't copy things you see done by others, especially on YouTube.



    So Lester does this conversion, swaps the board into a 98VHP to drop in 4 2SC2879's and according to him there was nothing else done and he's getting about 800 watts peak. So, Chop being the busy body that he is, picks up a 98 and says if he can do it, so can I. Not exactly. Somebody isn't being completely truthful out there... Seems he's not the only one doing it and getting these high wattage readings. So...

    I'm seeing 500-600 PEP. The average reading, I'm seeing 300-350 and occasionally I'll hit 400. So, what y'alls take on this? I know someone else around here did this and was laying claim to the biggest Galaxy in the world but I can't recall who it was. Seems like that guy said 600 watts at some point. So how is Lester getting 800 watts and his power supply is showing a drop in voltage to around 12 or so volts?

    I can usually smell a lie like a fart in a car but my sniffer has been stopped up for awhile now...
     

  2. StrangeBrew

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    Not a tech so take this with a grain of salt but 800 watts out of 4 2SC2879's doesn't seem like a reasonable number to me.
     
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  3. TheRealPorkchop

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    Well I'm not a "tech" myself and it doesn't seem possible to me, not without a whole lot of drive. More than a radio anyway. But Lester isn't the only one claiming that or showing that, he's just the only one I'd trust farther than I could throw him.
     
  4. Robb

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    'Whole lotta Drive' is what has destroyed many of the genuine Toshiba 2879's in order to extract nothing more than some extra dirty watts.

    Sounds like it should be the name of a Led Zeppelin song rather than the name of the term for the demise of these quickly disappearing transistors.

    People aren't going to hear you any better with 800w than they will with 500w - as it was spec'd to do by design/longevity . . .
     
    #4 Robb, Oct 11, 2017
    Last edited: Oct 11, 2017
  5. TheRealPorkchop

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    I didn't say I was cram a whole lotta drive into it, I just said I didn't see how it'd get it without that.

    Which makes you wonder, yea it makes me wonder.... what about a 2x4? That's a lot more drive than any Ranger chassis is gonna put out and they don't destroy themselves.

    The point to this is about how those other people are getting that 800 watts or more out this swap, not what I'm getting or what's safe to protect the mystical 2879. I will absolutely agree with you 110% that you won't be heard more between those two power figures within a given distance and condition. Again, I'm just trying to figure out what is they did versus what they told they did.
     
  6. Robb

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    A 2x4 is an AM only box with only competition in mind.
    Think about it all for just a second.
    Each 2879 requires NO MORE THAN 10w/ea. Soooo, someone shoves a couple of 100w pills in front of four pills - and - then how much are they being over-driven? Do the math. Waaay over-driven and then a very short life expectancy. SO much for competition-style amps . . .

    BTW - the #1 cause of amp failure is not a bad SWR; it is over-driving the pills.
    Fact.
     
    #6 Robb, Oct 11, 2017
    Last edited: Oct 11, 2017
  7. TheRealPorkchop

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    Well I wasn't exactly arguing with you about it and I'm not even disagreeing with you about it. My personal opinion is I don't really care about the amount of them left, there's other options out there. And of course there's a whole debate on that as well but I don't even care about that either.

    My personal radio for my truck has remained the same for the last 14 years, a Magnum S9. The 2312's finally give up and I'll just swap in some mosfets and move on. I don't really have a need for an amp, this 98 is just a project and something to waste time on and obviously money too.

    The $64,000 question remains how Lester or anyone else is showing this 800 watts and he's done it on a Bird. So think about that for a minute. I've not seen where anyone else has questioned this so I guess the curiosity makes me the first? It seems very impossible to me and makes me wonder if there's some trickery going on. And then I'd say what happens if you buy this 800 watts miracle radio and you can't reproduce the magical wattmeter readings? Surely you'd call and question it.

    Personally I think it's BS and not possible but if there's that one chance it's not, then how's he doing it? That's all I want to know.
     
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  8. Robb

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    Well, I know one way they get more watts out of any amp.
    They feed the amp 18-20v instead of 13.8v.

    The 'other way around' blowing/replacing these transistors is not practical. The DEI replacement transistors can't hold a candle to the original Toshibas. They cannot be over-driven at all; they just pop. Can't be over-volted either. Don't really have the same reliability - in general.
     
    #8 Robb, Oct 12, 2017
    Last edited: Oct 12, 2017
  9. TheRealPorkchop

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    Have you seen the video in question?
     
  10. Robb

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    No; got a link?
     
  11. TheRealPorkchop

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    In this one, I believe the claim is 900 watts

     
  12. Robb

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    One thing wrong with that. How can you get 900w out of a 40 amp power supply @ 14.5v? ANS: you can't.

    Surprised that LesComm didn't comment on that one.
     
    #12 Robb, Oct 12, 2017
    Last edited: Oct 12, 2017
  13. TheRealPorkchop

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    Well he's doing it, right there in that video. Now you see my question? I'd like to know how is he doing that?

    Assuming what he showed and what he did was only change out that mosfet board for a transistor board and drop in those Toshiba's, then I've done the same thing. And I'm running mine on a 125 amp Cosel supply at 14.2 volts and I'm not seeing those numbers, especially that peak reading.

    I expected to see an increase by making the changes I've done, I didn't expect to see what he's showing. But I do question how he's getting those numbers. And if it's all a big show, there's gonna be a lot of pissed off and disappointed customers cause that's not the only radio he's done that way and shot video of. He's done it to a 2970 too.
     
  14. TheRealPorkchop

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    Not that it makes it any better but he states it's a 50 amp supply, haha, just wanted to throw that in there. And here he goes again...

     
  15. Robb

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    No; he not doing it right.
    It is physically impossible to get that much wattage out of a 40 amp power supply.

    To get 900w out of that radio, you would need a power supply that would put out over 100 amps @18v. In that video - under load (keyed), the power supply showed only 12v. It goes against the laws of physics to see that radio put out 900w. Has to be something wrong with his test setup to get those numbers.

    Anyone else see these same faults in that video?
     

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