[RFI] Aims 5000 Watt MSW Power Inverter

Craig Warnol kb5uej at amsat.org
Mon Sep 15 14:04:41 EDT 2008


I understand your line of thinking, but let me throw this out.  I 
thought about the same thing until I looked at the numbers. I bought a 
Coleman Powermate 6250 for ~$400. Just before Hurricane Ivan hit us in 
2k4. This generator puts out 5KW surges to 6250, and runs 11 hours on ~ 
5 gallons of gas. How much gas would it take to run a vehicle at 2000 
rpm for that time? Most alternators in vehicles need a minimum 1500 rpm 
to generate output. See attached image (This is for a 200A Powermaster 
CS144 GM // alternator.) To get 200A out of it, you would have to keep 
your vehicle running ~3500 RPM. You would need two of these in addition 
to your normal alternator to be able to be able to supply the 416A+ 
required to put full load on that inverter.

Craig (KB5UEJ)

kd4e wrote:
> This has nothing to do with Amateur Radio, I am sorry
> if I was unclear.
> The primary purpose would be on the rare occasion where
> a tropical storm or tornado knocks out power.
> It would power the fridge or a small ac or lights until
> power is restored.
> Since we already maintain the engines in two vehicles
> and they have large fuel storage it seems inefficient
> to also maintain a generator for rare use.
>>> They draw a LOT of current at 13.6 VDC.  In this case, at 5000 watts 
>>> output @ 90% efficiency, the input draw will be 408 amps!!!  
>> I'll second all of Dale's comments, and add this. What is your final 
>> objective? If you could be happy with 500-600 watts RF output on the HF 
>> bands, I strongly suggest that you look at a power amp like the Ten Tec 
>> Hercules II that will be very happy supplying full output pulling 70-80A  
>> from a 13.8V DC source. It takes only about 25W to drive to full power, 
>> so the transceiver will add only another 10A. And that's keydown -- 
>> average current will be a lot less. You could probably buy that amp used 
>> for about what it would cost to buy an inverter and clean it up enough 
>> to actually use it in an HF station. Yes, legal limit power is another 4
>> + dB up from there, but at what cost? If you can't hear 'em, you can't 
>> work 'em!  I don't know what other DC amps are on the market, but I'd 
>> bet that there are others. I have a Herc II. It's a very nice amp. 
>> 73,
>> Jim K9YC

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