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How much can i drive a dave made amp

Discussion in 'Amplifiers' started by Reinaldo ortiz, Jul 14, 2019.

  1. Reinaldo ortiz

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    Hi friends, recently i purchased a Dave made amp with 2. 2SC2290 TOSHIBAS driving 4. 2SC2879 TOSHIBAS im using a Stryker SR 955 HPC , thanks in advace for your Advice


     

  2. dave457

    dave457 Sr. Member

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    That radio is to much for that configuration
    A single final radio should work
     
  3. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Unless there is a way to turn the power down on the 955, you would be better with a 4 pill amp. That radio is too much drive for the 2 pill driver.
     
  4. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    Agree with the above postings.
    You need very little drive for that 2x4.
    Find a single final AM Radio, like a cobra 29 to run with it.
    Be nice to those 2879's
    They are expensive to replace now days.

    73
    Jeff
     
  5. w9cll

    w9cll W9WDX Amateur Radio Club Member

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    Boom!
     
    AudioShockwav and Reinaldo ortiz like this.
  6. nomadradio

    nomadradio Analog Retentive

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    The two 2SC2290 transistors that RCI used for years in the Galaxy Turbo, Eagle 5000, 2990 and other radios never got more than 14 Watts peak drive from the radio circuit board inside it. A mean one would show 16 Watt peaks if you turned off the radio's amplifier. That's how much drive the RCI factory thinks you need for a pair of 2SC2290.

    I ask people if they know what "High Drive" means on a linear.

    Whatever they answer, it's never the right one.

    The phrase "High Drive" on a CB amplifier means one of two things:

    1) We knew you wanted to see this so we printed it on the front.

    -- OR --

    2) Please blow it up and come back to buy another one soon!

    Time to decide which of these two pieces you like best.

    If you like the radio better, it's time for a bigger amplifier. I would recommend a straight 8-transistor type.

    And if you like the amplifier better, a radio like a Galaxy 959 is better suited to it.

    But they won't play well together.

    73
     
  7. Reinaldo ortiz

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    Thank you, im goin to try adjusting the radio limit of modulation to see if i could control the output no i could lower it to 1.5 watts dead key and it modulates 40 watts ill see if the limit controls the swing, but how much could it handle in the limit wattage?
     
  8. nomadradio

    nomadradio Analog Retentive

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    All you need is a dummy load to soak up half or two-thirds of the radio's drive power, and feed the rest of the power to the amplifier.

    It's called a power attenuator.

    Sure sounds like something somebody ought to be making and selling.

    Turning the radio down enough is probably not the way to go.

    73
     
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  9. 999

    999 Well-Known Member

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    With 40 watts into that box you will be letting the smoke out, no matt how low you make the dead key.
    Do not pair that radio with that amplier.
     
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  10. 543_Dallas

    543_Dallas Sr. Member

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    The easy solution is to bypass the driver inside the amp. It will take about 10 minutes and is reversible.
     
  11. Reinaldo ortiz

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    Thanks ill be researching
    Thanks Friend i researched the attenuators and my only question is does it not affect the radio, and if not ill give it a try, and in last resort ill bypass the amps 2 pill drivers and let it only with pills
     
  12. AudioShockwav

    AudioShockwav Extraterrestrial Admin
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    453 has the best solution if you are dead set on keeping the 2x4.
    Kind of a bummer that you now have a amp with 2 extra transistors that do nothing.
    There is one other option.
    Sell the 2x4.
    I don't think it will be hard and there are lots of guys out there that will go ape sh*t for it just because it says Dave made (more likely Joe made but that is a different post) and put the money into a straight 6 or even better a 8 transistor amp.
    I do not like ANY amp with built in driver sections.
    That is just my opinion.
    Back when we all had 23 channel radios that struggled to do 3 or 3 and a half watts and you had a Amp with more transistors like a TNT 12 pack or some of the Messenger multi transistor amps then a driver made some sense.
    By the time we got to dual final radios , not to much.
    The 1x2 and 2x4 Amps that started showing up were just bucking Broncos waiting to go off.
    2879's can take a lot of abuse but if you start driving them that hard and don't have all your ducks in a row it invites magic smoke.
    When pressed hard things like reflected power can become critical in the life of a transistor.
    73
    Jeff
     
  13. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    I have to play devils advocate on this one, I can’t help myself. While I agree it’s nit the best of ideas I also have to disagree and say it won’t destroy it instantly.

    Back when the Magnum S9 first came out everyone said you could run a 2 pill behind that. Rubbish. I did it and did so daily for almost 15 years, still have the radio and the amp in untouched condition.

    What’s that? Oh yeah that’s not a 655/955 radio, you’re right. But I have a friend that has a 655 and it has a 2 pill behind it, he’s a motor mouth and a truck driver. He’s been doing exactly that for over 2 years, maybe closer to 3 now, I’ve gotten older so cut me some slack. He’s had zero issues, no concerns, no problems and I mean he talks.

    So while it’s not the best of ideas and technically wrong going by a spec sheet, it’s not absolutely destructive. At least not in this part of the country and under whatever special conditions he has happening. And I’m definitely not going against anyone that’s posted a response here or challenging their knowledge/experience. I’m only stating what I’ve witnessed firsthand.
     
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  14. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    One of our locals has a Lincoln 2+ and a 2x6. Needless to say, when he keys up he is about 20 channels wide.
     
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  15. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Oh I’m sure the guy I’m referencing is also a few channels wide, I haven’t checked to see. And I’ll say again that it’s not the greatest idea anyone has ever had to run a setup like that. But even though, it’s possible to do it and it’ll last, I guess it’s given up to good tuning far as input to the amp and antenna go.

    I will agree that you’d be better off bypassing the driver section or just getting a straight 4.
     

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