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  #9  
Old 05-16-2011, 10:22 AM
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Assuming the amplifier could handle it (and it won't) a doubling of source voltage would increase output power by a factor of four. This is just Ohm's law since doubling voltage will also double current into the same load. Keep in mind the output impedance should remain virtually the same under these conditions and that volts times amps is watts.

The 800 watt PEP amp would try and produce 3.2 KW PEP! Going from 12 to 18 volts should double power at 1.6 KW. In this situation each volt is producing about 133 watts of extra output. Every watt you try and squeeze out past the 800 will come at the expense of spectral purity due to rapidly increasing IMD. The people you talk to may not notice it but those using frequencies adjacent to yours probably will.

Class AB1 is only given to tube amplifiers because the "1" indicates there will be grid current flowing. The equivalent class of bias for transistors would be AB. The drive suggestions and test for linearity that VA3ES suggests are right on target. The amplifier should only draw about 100 amps. Having 200 amps available is a great idea since it will reduce voltage drop and provide plenty of headroom for the positive peaks.

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  #10  
Old 05-16-2011, 10:28 AM
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Quote:
Originally Posted by Shockwave View Post
Assuming the amplifier could handle it (and it won't) a doubling of source voltage would increase output power by a factor of four. This is just Ohm's law since doubling voltage will also double current into the same load. Keep in mind the output impedance should remain virtually the same under these conditions and that volts times amps is watts.

The 800 watt PEP amp would try and produce 3.2 KW PEP! Going from 12 to 18 volts should double power at 1.6 KW. In this situation each volt is producing about 133 watts of extra output. Every watt you try and squeeze out past the 800 will come at the expense of spectral purity due to rapidly increasing IMD. The people you talk to may not notice it but those using frequencies adjacent to yours probably will.

Class AB1 is only given to tube amplifiers because the "1" indicates there will be grid current flowing. The equivalent class of bias for transistors would be AB. The drive suggestions and test for linearity that VA3ES suggests are right on target. The amplifier should only draw about 100 amps. Having 200 amps available is a great idea since it will reduce voltage drop and provide plenty of headroom for the positive peaks.
Thanks guys for the very helpful info....

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  #11  
Old 05-16-2011, 11:53 AM
BOOTY MONSTER
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nice to see some common sense and technically correct comments on driving amps/pills . but .... i dont think any one buys those class C amps to have a clean tx . they want their meter to swing as far to the right as possible and clarity is a afterthought , if its matters at all to them . and the fact that even doubling power has a negligible effect on their tx is ignored if favor of how far the needle swings .

i know , i know ..........
couldn't help myself

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  #12  
Old 05-16-2011, 12:32 PM
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well i can tell you from experience that i run a 2x8 class c box on 14.50 volts using a 29 classic i get 800 bird watts on 19 volts i see 1500 bird watts
driver=2 2879 final=8-2879 on a test i did i only bleed 6 channels up and 6 down compare to guys that take the whole 120+ channels as a matter of fack shockwave has heard me on this box and i trust his judgement that my 2x8 is clean sounding compare o others out there i've notice that it all comes down on who ever built the box what cheap componets they use or short cuts they take.
i love it when guys swear/claim their 8 pill does 2000 to 2200 bird watts if i can listen to my car stereo while talking on the pill and it doesn't come thru my speakers i consider that been some what of a clean box.??

Last edited by 1iwilly; 05-16-2011 at 12:56 PM.

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  #13  
Old 05-16-2011, 12:54 PM
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on a test i did i only bleed 6 channels
__________________
From milliwatts to kilowatts its all cool to me .... but life is to short for QRP !!

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  #14  
Old 05-16-2011, 01:20 PM
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"Only" 6 channels is still a whole lot of splatter.. a WHOLE lot. Not at all what I would call clean.. Perhaps a bit clean for an unfiltered class C box though.

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  #15  
Old 05-16-2011, 01:34 PM
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my farts smell pretty good compared to a dead animal with maggots oozing out of it .
compared to a rose they're not so nice .

consider the context of what the comparison is based on .

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  #16  
Old 05-16-2011, 01:44 PM
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Quote:
Originally Posted by eagle1911 View Post
"Only" 6 channels is still a whole lot of splatter.. a WHOLE lot. Not at all what I would call clean.. Perhaps a bit clean for an unfiltered class C box though.
he wanted to know what to expect out a 8 pill so i gave him an example of what i get out of mine.!

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