how can a 50 amp power supply allow a amp to do 750 watts ?

[BOOTY MONSTER]

http://www.worldwidedx.com/cb-radio-gear-swapshop/138998-fs-davemade-1x4.html

1*2290 x 4*2879

Performance -
RMS: +/- 300
PEP: +/- 750

Testing Parameters: Hooked up to an Astron 50A Power Supply. Driven by an Export radio into a 500w dummy load. Measurements takes on a Bird 43 with Bird 2500H element. PEP measured on Bird 43 w/ Bird Peak Kit.

Recently re-capped w/ matching caps

Upgraded to 4AWG & comes with the Anderson 175.


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how can a 50 amp power supply allow a amp to do 750 watts ?

 

[psycho]

Just because the meter is a Bird 43P doesn't mean it's tight. Bird 43Ps, in the peak hold mode, are as generous if not more generous than a Dosy. Besides we know Davemades have louder audio and do mo' watts, at least on other forums.

 

[TonyV225]

LMAO!! @ Psycho!! As said before, "On the 11 meter band or some meters or simply in some peoples minds the laws of physics do not apply"

 

[gamegetter]

you would be pushing the power supply to it's max and you would need 15 volts at 50 amps draw...


but i would expect oscillations from the amp<More audio>

better off to coast it with a clean signal

 

[W5LZ]

Don't be so silly!
Of curse it's that #4 pretty red wire that's the reason. It's very close to pink, and electrons (charged electrons!) behave differently near pink...
- 'Doc

 

[gamegetter]

We need a pink frog for Doc!
:wub: this is the closest we have.

 

[Shockwave]

The simple reason is on AM the change in current drain between carrier and modulated PEP is very small. The current may double on positive word peaks but it drops to zero on the negative peaks so the average current drain on the power supply remains fairly stable and close to the carrier condition.

The Bird peak meter is not generous either. It's one of the few that meet the requirements of being externally powered so they can display peak power. All meters that claim to be peak without having a battery or power supply to run the meter, always fall short of the true PEP power or exaggerate the carrier.

One should also consider these numbers are high for what I assume would be 13.8 volts. The only way to get that power off four 2879's on this lower voltage would be to drive the heck out of it and I'm confident that was done with a 2290 and export rig.

50 amps is also the most current that four 2SC2879's in push-pull can ever draw before blowing up. They handle an absolute maximum 25 amps of collector current per device. Only one is active at any given time in each bank of two with a push-pull circuit. Each bank of two could draw up to 25 amps and no more. This does not include the current to feed the 2290 driver.

 

[Wire Weasel]

Yeah, what he .... they ..... said.

 

[Captain Kilowatt]

you would be pushing the power supply to it's max and you would need 15 volts at 50 amps draw...


but i would expect oscillations from the amp<More audio>

better off to coast it with a clean signal

15 volts X 50 amps = 750 watts DC INPUT

So that amp runs at 100% efficiency hey?

Figure current peaks of nearly 100 amps for 750 watts peak output.

 

[Captain Kilowatt]

how can a 50 amp power supply allow a amp to do 750 watts ?

This is 11m. Anything is possible.

 

[gamegetter]

15 volts X 50 amps = 750 watts DC INPUT

So that amp runs at 100% efficiency hey?

Figure current peaks of nearly 100 amps for 750 watts peak output.

thanks for catching that, that makes the original figures even more preposterous.

 

[Shockwave]

It's really the volts that are lacking to achieve the 750 watts peak because the four output transistors can't take more than 50 amps. Now if he had it on 18 volts there would be no problem reaching more than 750 watts PEP while maintaining under the 50 amps average current draw.

 

[gamegetter]

and that supply is rated at only 12 to 15 volts if i recall right.

 

[ExitThirteen]

Since it is class C junk, the box will be more efficient than something that's biased AB, but even at class C, you're only talking about 60% efficiency. So yeah, dunno how that Astron was able to keep up with the amp.... or how those numbers with the amp were even possible.


~Cheers~

 

[dxhound]

Im surprised no one has said anything about the condition of the signal out. Shockwave could correct me if im wrong, but if the signal is distorted and overmodulated (i.e. a square wave) the meter will sample more peak duration of the wave and thus show an elevated reading on the meter.

This would be a good test of the bird 43p. I dont have the Peak kit, otherwise I would try this with a function generator. It would be interesting to see if the square wave affects the reading or simply reads the peak of the square at its most positive point like it would with a sine wave.