I need a 100W Power amplifier for 1-20 MHz, any ideas?

Discussion in 'General Electronics Chat' started by zero_coke, Feb 5, 2013.

  1. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
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    Does anyone know where I can possibly get a kit of some sort for an amplifier with such specs?

    1-20 MHz, 60-100Watts output
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    That is an extremely wide bandwidth. What is the application?

    A 20Mhz bandwidth is more straightforward when amplifying 900Mhz to 920Mhz, for example. At the lower frequencies, you would be amplifying AM radio stations, Ham operators, and others. The FCC wouldn't be happy about that, discounting the engineering issues.

    The reason for it being more complicated, check impedance of a capacitor at 1Mhz, then 20Mhz, compare to 900Mhz and 920Mhz.
     
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    That is going to be REALLY hard to do. I recall that the video amplifiers in TVs needed an amplifier stage that had a bandwidth of about 6 MHz and that took some serious tweaking and those were not power amps, just video amps.

    One place to get wide band amp designs is in oscilloscopes. Some have bandwidths exceeding 200 MHz.
     
  4. Papabravo

    Expert

    Feb 24, 2006
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    There are commercially available amplifiers which work in the 80,40,30,20, & 17M portions of the amateur bands. It seems there are restrictions on amplifiers that come close to the 11M citizens band. There are few if any kit makers left so I'm afraid you're pretty much out of luck. I'm still curious about what you would do with such a device.
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    60 to 100 Watts is a lot of power.
    What do you want to do with such?

    Here is a kit for 30 Watts, wich is already quite some power:
    http://www.box73.de/product_info.php?products_id=2382

    Bertus

    PS I would NOT put the power to the open, as the telecom authority will find you and possibly give you a large fine.
    Where I live the fine can be upto 1200 Euro AND all equipment will be taken.
     
  6. chuckey

    Well-Known Member

    Jun 4, 2007
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    That kits rated at 30W p-e-p not rms, so thats about 4W rms!! About 45 years ago, I was involved with a military pack set, the PA was a pair of 2N2887s, running 40 V at 1 A to get 12Wrms out over 2-12MHZ. There was also a 100W linear amp. So for 100W out, you would need 8 modules, so thats 40 V@ 8A, thats a lot of power to get rid off. So the linear was a brass box totally filled with oil and bolted to a large heat sink. Devilish thing to test, the modules were hung on a crane and dunked into a kitchen sink full of oil, and the modules were left to drip dry on the draining board!!
    With high speed devices now, a better way to go would be to build a class D amplifier, its still pushing technology a lot.
    Frank
     
  7. bertus

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  8. Kermit2

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    Feb 5, 2010
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  9. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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  10. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
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    Hey guys :)

    I'm doing the wireless electricity experiment thing that MIT has done, except I need to amplify my weak AC signal oscillating (we haven't settled on a frequency yet, but it is going to be between 1 - 20 MHz). So yes, we need to amplify the signal and we're expecting 10% efficiency so if we put in say 100W we would be lucky to get 10-15 W at the output where we can do some useful work with it.
     
  11. Externet

    AAC Fanatic!

    Nov 29, 2005
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    I do have a 100 Watt amplifier 1 MHz to 30 MHz.
    If you are interested, you could contact me atexternetatinorbitdotcom.
     
  12. chuckey

    Well-Known Member

    Jun 4, 2007
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    If you want a fixed frequency RF source now, THATs a lot easier to do. Consult the AARL or RSGB handbooks - radio amateur handbooks very good for transmitters from 2 - 150 MHZ.
    Frank
     
  13. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
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    Well, isn't that what Royer oscillators do? They're just high power oscillators no? Right now I have my oscillator hooked up to a power amplifier because what I'm trying to do is create an oscillating magnetic field at high power at a certain frequency which is unknown right now...its between 2 and 20 MHz. I thought of creating an oscillating circuit at high power like the Royer but it seems like the flexibility on frequency is not very good...
     
  14. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    What is the diameter and length of your coils, number of turns, and spacing? What size conductor are you using for the coils?

    If you have access to an LCRZ meter, you may get close by getting an idea of the inductance and capacitance.
     
  15. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
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    I'm using 30 cm diameter coils. My driving coil is 1 turn, and its inductively coupled to my resonant coil of 9 turns, same diameter throughout for all 4 coils. Two on sending end, and two on receiving end. Middle two are resonant. Outer two are inductively coupled to the resonant coils. Resonant ones have 9 turns and inductively coupled ones have 1 turn. I want to send power wirelessly to the load at a 50 cm gap between them which is why I need to pump out some power at the source end. I calculated the inductances to be 0.69 uH for outer two and 14 uH for inner two. Spacing of resonant ones is about the same thickness of the coil, which is quarter inch copper tube is what I'm using.
     
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