yeah funbiz, besides a few blemishes it looks bran spankin new. have fun keying on the whole world with that thing brother. 73's
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My new amp
- Thread starter funbiz99
- Start date
Based on alternator, transformer, and amplifier efficiencies and cabling losses, I'm guessing you are going to need a few more than 4 alternators to get anywhere close to 20kW out. Have fun powering that bad boy...
funbiz99 said:
Four 12V, 250A alternators produce approximately 12kW. Assumming 100% efficiency, which is not even close to possible, where are you getting the extra 8kW from? I doubt the four 1.5 amp power supplies are doing this unless they are rated at greater than 1333 volts rms.
Again, this is just the energy needed to generate 20kW out and does not take into account other losses and equipment efficiencies...
I am not a technician by any means....I do know that i can get 7000 plate volts and pull 3.5 amps while turning 4000+ rpms...7000x3.5=24500...now maybe these are false meter readings and my bird 43 (showing around 25000) is not working. i really dont know. wish i could explain it better.
funbiz99 said:
Let me simplify my analysis. If everything was 100% efficient, and the alternator put out 15 VDC, then the alternators would still need to generate about 1333 ADC for 20kW to be transmitted. Now throw some losses in there, and the bias of the amp, and lets say the system efficiency is around 60% which is quite good for a cascaded high power system, and the current would need to be around 2222 ADC. The power drawn from the source will always be quite a bit larger than the power transmitted, so with 60% efficiency, the power from the source will be about 33.33kW. Now if we divide this value by 746W, we see that it will take about 44.68 HP to generate this much power from your engine every time you key...
I'm guessing if you are only keying for a few seconds on an intermittent basis, then you might be able to get by with pushing the limits of the energy components without failure. But if you plan on communicating at 20kW for any length of time, I would upgrade the power system to ensure durability, realiability, and for clear comminications.
funbiz99 said:
I was just using 15V because that is what you said (see where I quoted you). As for an alternator being 3-Phase, I know this. If the rectifiers are removed they will generate an AC voltage that can be stepped up with a transformer, but the bottom line is that the laws of physics cannot be violated - energy cannot be created or destroyed only moved around.
Power Out = Power in - Power Losses, or more correctly the units should be volts x amps...
Since every system has losses, the alternator(s) and battery(s) would need to be able to produce much more than 20kW when keying for hours at a time.
Now if we assume a 60% overall system efficiency, the power system would need to produce approximately 33.33kW for hours on end. This means that 13.33kW is wasted power and therefore converted to heat. If this wattage is converted to BTU/Hour, the amount of heat generated would be about 45,500 BTU/Hour. I'll bet you get pretty warm when keying for hours.
I'll bet you are measuring PEP and not Average with your power meter. If this is the case, and you are 100% modulated, your Average power is only around 7.5kW for a 20kW PEP signal. This would explain alot since the only true measure of power is average and that is what I was basing my calculations on.
funbiz99 said:
I haven't had anything explained to me yet... Though I have gleaned some insight into what the system is used for and how it is designed.
:?