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2m max TX power?

Discussion in 'General Ham Radio Discussion' started by ke7vvt, Oct 10, 2009.

  1. ke7vvt

    ke7vvt
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    Is the 50W max transmit power on 2m,

    1. 50W coming out of the radio

    or



    2. 50W ERP coming out of the antenna?
     

  2. W5LZ

    W5LZ
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    That 50 watts may be the max for your radio but not for the band. The power limit on 2 meters is 1500 watts.
    - 'Doc
     
  3. ke7vvt

    ke7vvt
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    I thought it was 50W at the radio, but 1500W sounds even better!

    Thanks!
     
  4. Moleculo

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    The FCC power limits are Peak Envelope Power, measured at the transmitter output. Since you can use gain antennas, the ERP may be much greater than that.
     
  5. W5LZ

    W5LZ
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    Crotchety Old Bastard

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    Don't get too happy with that 1500 watts thingy, it is definitely NOT easy to do at VHF. :)
    - 'Doc
     
  6. ke7vvt

    ke7vvt
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  7. HiDef

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    With a 75 watt transmitter you will have 75 watts as far as the regulations go.

    The regulation is transmitter power out not effective radiated power. There are hams who have 300,000 watts ERP on VHF legally.

    The amateur service is designed so experimentation is encouraged. This is why there is no limit on ERP.
     
  8. kd-5-bgt

    kd-5-bgt
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    W9WDX Amateur Radio Club Member

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    I dont think you would be able to get close to 1500 watts from a 75 watt radio and a 7 db gain antenna......

    I know there is a formula for figuring the added power that an antennas gain provides but I dont remember what that is off hand,maybe someone here can enlighten me/us on that

    I have seen 1 kw + amps for VHF/UHF but those are very high dollar....
     
  9. n8fgb

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    Don't know what you need 75 watts on FM for though.Once you facter in feedline loses, every 3db is a doubling of power. Just don't forget to calculate the exopsure levels, they are more critical at those frequencies than on HF.
    Rich
     
  10. Captain Kilowatt

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    7dBi about is the same as 5 dBd which has a multiplication factor of about 3.2 so therefore 75 watts times 3.2= 240 watts minus any losses due to coax length and SWR.

    Don't get transmitter power and ERP(Effective Radiated Power) confused. The max TX power allowed on 2m is 1500 watts.Max ERP is whatever you have the room for to erect a big enough antenna.

    This array at W5UN has an ERP of 1.5 MILLION watts when driven with 1500.


    [​IMG]
     
  11. Beetle

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    What everyone's trying to tell you is that the antenna gain is NOT part of the equation. Your power limit is 1500 watts. You can feed up to 1500 watts of RF from your transmitter to whatever antenna you want.

    Your 75 watt radio is a 75 watt radio. You'll be about 1425 watts short of the allowable maximum output but with a decent antenna you probably won't even NEED any more than 75.
     
  12. kd-5-bgt

    kd-5-bgt
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    W9WDX Amateur Radio Club Member

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    :blink: WHOA!! Now that is an antenna set up !

    And yes the power allowance is transmitter power,not the power that is figured at the antenna...sorry if I was misunderstood.....sometimes I make no sence to anyone but me :whistle:
     
  13. Moleculo

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    Can someone tow that array over to my driveway? I have a few experiments I want to run. hehehehe.
     
  14. Captain Kilowatt

    Captain Kilowatt
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    Actually Mole that is how the array is moved. He has a motorized tractor of sorts that rotates the entire thing around a central point.It runs on two narrow concrete tracks around the perimeter.
     
  15. Beetle

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