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The next generation of linear amplifiers has arrived.

Discussion in 'Amplifiers' started by Shockwave, Sep 5, 2019.

  1. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    You also said that pep output would not stress the fuse. I have seen MANY fuses fail from fatigue due to being run at or very slightly over their limit. Constant heating and cooling of the fuse in a dynamic power circuit such as pep service causes the fuse to fatigue from constant heating and subsequent expansion and contracting. It will eventually break free from the point it is soldered to the end cap. Sure it won't blow and you will need an ohmmeter to see if it is any good but it will fail. Eventually. Again.....stating the amp is capable of 750 watts in either pep or CW modes then saying that a 5 amp fuse will support full pep output is implying it can also sustain that same 750 watt power output in CW mode.


     

  2. Handy Andy

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

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    Welcome to the "Bond-able" society...

    Unless you are self-employed, the fruits of your labor are for the praise of the stockholders and CEO - their answer to the question of "What about me?" - is...

    ... "You work for us - or aren't you willing to anymore?" ...

    Fine Print and Lawyers - the signature is the 3rd party...
     
    #32 Handy Andy, Sep 6, 2019
    Last edited: Sep 6, 2019
    AudioShockwav likes this.
  3. Handy Andy

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

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    Before this gets too confusing...

    IF you still have the unit - pull that 5-Amp fuse...

    Is it (that fuse) AGC or Slo-Blow rated?
     
    Redbeard U812 likes this.
  4. Shockwave

    Shockwave Sr. Member

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    It is fast acting and was intentionally chosen as the smallest fuse that could run the amplifier during the testing and alignment process. Since some are having a hard time with that 5 amp fuse, we can go one step further and mention it was operating close to that PEP output on a 3 amp fuse prior to connecting any bias and deep into class C. As the conduction angle decreases, average current drops significantly.
     
    #34 Shockwave, Sep 6, 2019
    Last edited: Sep 6, 2019
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  5. Mudfoot

    Mudfoot Sr. Member

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    I find this very interesting. I appreciate what you've shared so far.
     
    AudioShockwav and Shockwave like this.
  6. nomadradio

    nomadradio Analog Retentive

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    So, if I understand right that 750W PEP AM signal represents about 188 Watts CW-equivalent "average" power, the reading you would see on a stock Bird 43 meter. An honest 100 percent modulation will only kick the Bird's needle upward a tiny bit above the carrier reading.

    Okay, at 50% RF efficiency, we would need twice that from the DC supply or 376 Watts of what they used to call "input" power back in the bad old days.

    To deliver 376 Watts of DC to the amplifier from a power supply that's 80 percent efficient will then draw 470 Watts from the AC wall outlet. Just under 4 Amps at 120 Volts, and at the reasonable upper limit for that 5-Amp fuse.

    The numbers work fine for the 750 Watt PEP AM situation.

    To get a 750 Watt carrier will require four times that, all other things being equal. A dedicated 20-Amp 120-Volt AC circuit would be okay for that.

    73
     
    Shockwave likes this.
  7. kopcicle

    kopcicle Sr. Member

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    I need a laundry ticket , I feel I'm about to be taken to the cleaners.


    All hype aside ...
    https://www.nxp.com/docs/en/data-sheet/MRF101AN.pdf
    So 100 Watts from a TO220 package isn't enough for you ?
    https://www.nxp.com/docs/en/data-sheet/MRF300AN.pdf
    A TO247-3 that produces 330 watts CW isn't enough?
    https://www.nxp.com/docs/en/data-sheet/MRFX1K80H.pdf
    1800 Watts from 65V

    Radio frequency amplification: the final frontier. These are the voyages of LDMOS technology, Its ten-year mission: to explore strange new worlds. To seek out new efficiency and new DX contacts. To boldly go where no bipolar junction transistor or Mosfet has gone before!

    In short , you'll have to spew more than hype to impress me . Then again , I'm an hack and who cares what I think ?


    [sarc] so all I need to achieve 750 watts pep (or CW ) is a 5 amp 125v fuse? You mean I've been wasting time and money all these years? [/sarc]
     
    #37 kopcicle, Sep 7, 2019
    Last edited: Sep 7, 2019
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  8. Shockwave

    Shockwave Sr. Member

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    Setting the bench up now for tomorrows AM and SSB two tone tests with video. I appreciate the skepticism and it's been great motivation. You'll clearly see the amplifier I've designed has a drive coax with a Bird measuring input power. The output coax will have another Bird measuring output power through an RF sampler feeding the scope. The last wire is the line cord where a pair of Fluke meters will be measuring line voltage and input current simultaneously. It will be displayed in a manner that makes it impossible to hide any other wires or tricks other than what is going on inside the new linear. If you can think of any way to hide something under those circumstances before tomorrow afternoon, speak up now and I'll consider it in the video.
     
    #38 Shockwave, Sep 7, 2019
    Last edited: Sep 7, 2019
  9. Highway Man

    Highway Man Active Member

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    pardon me, has this anything to do with the recent statements made by BBI concerning a new style amp?
     
  10. Highway Man

    Highway Man Active Member

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    oh, and please share the video here when it drops.
    Thanks
     
  11. Highway Man

    Highway Man Active Member

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    and from what I gathered it was LDMOS
     
  12. 543_Dallas

    543_Dallas Sr. Member

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    I'm not completely sold on solid state yet. I've been seeing too many hams putting out a signal as wide as a barn door with their new solid state amps. One guy, that is local to me, uses on a late model flex and expert amplifier. The IMD sucks unless you really pull the throttle back. Adaptive predistortion may become a necessity.
     
    Shockwave likes this.
  13. Shockwave

    Shockwave Sr. Member

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    These are the final voyages of LDMOS. They are already becoming obsolete. Their 50 volt requirement is inconvenient and no longer needed with today's new technology. All of the advancements with lower current and improved IMD with easier output matching, have only gotten better in the next generation.
     
  14. Shockwave

    Shockwave Sr. Member

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    That may have a lot to do with the rig in front of that solid state linear and how its driving it. Flex radios are very easy to set up in a way that makes them as wide as a barn door too. Garbage in, garbage out. Running the device below 50% of its dissipation is good practice and helps keep IMD acceptable as in the case of this amp.
     
  15. Highway Man

    Highway Man Active Member

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    it was mentioned that no power supply was needed
     

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