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Author Topic: power requirements for Ameritron SPS-75MV  (Read 1267 times)
N2CV
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Posts: 15




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« on: July 04, 2017, 01:04:22 PM »

Does anyone know how the power input for AMERITRON SPS-75MV power supply?  I purchased a Harbor Freight Tailgate 900/700W portable generator this morning for $89.00 (Independence day Sale Only) and do not want to open the box until i know it is sufficient to power my power supply.  My power supply Has been plugged into a 15A 110V outlet for the past year and works flawlessly.  I went through the manual it only specify the power supply will work with any 110 or 220 v outlet.

Info on the generator can be found on Harbor freight's web site - https://www.harborfreight.com/900-peak700-running-watts-2-hp-63cc-2-cycle-gas-generator-epacarb-63025.html 

73,
Al
N2cv
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W9IQ
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Posts: 1405




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« Reply #1 on: July 05, 2017, 12:55:10 AM »

If you fully load the output of your power supply, you will be drawing 1,150 watts (13.8 volts * 75 amps). Then if you factor in a 90% efficiency it rises to 1,278 watts. So at this level of power consumption, your new generator will not have enough power.

But it likely you are not drawing the full 75 amps so calculate your total load and repeat the math to see if you come into range of what the generator can supply.
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
W8JX
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Posts: 11802




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« Reply #2 on: July 05, 2017, 06:40:55 AM »

If you fully load the output of your power supply, you will be drawing 1,150 watts (13.8 volts * 75 amps). Then if you factor in a 90% efficiency it rises to 1,278 watts. So at this level of power consumption, your new generator will not have enough power.

But it likely you are not drawing the full 75 amps so calculate your total load and repeat the math to see if you come into range of what the generator can supply.

I have a friend that also has a Harbor Freight 900 watt generator but we discovered it does not like big switching supplies. When he attempted to use a Stanley brand 40 amp automatic car battery charger hooking up to it it would hog down generator and kill it quickly. I would not hook that large a power supply to a 900 watt generator in question. I would suggest a 30 amp switcher tops.
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Ham since 1969....  Old School 20 WPM Extra
N2CV
Member

Posts: 15




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« Reply #3 on: July 05, 2017, 02:45:51 PM »

Thanks for the feedback.  I couldn't wait and opened the generator this afternoon.  I was able to power up my smaller Alinco 30A power supply and my Yaesu FT991 and without any problem.  Think this will be a keeper.

73,
Al
N2CV
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N3QE
Member

Posts: 4630




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« Reply #4 on: July 05, 2017, 06:47:45 PM »

I have a friend that also has a Harbor Freight 900 watt generator but we discovered it does not like big switching supplies. When he attempted to use a Stanley brand 40 amp automatic car battery charger hooking up to it it would hog down generator and kill it quickly. I would not hook that large a power supply to a 900 watt generator in question. I would suggest a 30 amp switcher tops.

The startup inrush current for a typical 1KW switcher will be 25 to 40 Amps and yes that's enough to stall dinky generators that are otherwise rated for most of a kW.
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W8JX
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« Reply #5 on: July 05, 2017, 07:17:24 PM »

The startup inrush current for a typical 1KW switcher will be 25 to 40 Amps and yes that's enough to stall dinky generators that are otherwise rated for most of a kW.

I do not doubt inrush is high but if it was that high it would be blowing a lot of fuses or breakers in house. I would say it is likely 1/2 that but that would still overwhelm that generator.
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Ham since 1969....  Old School 20 WPM Extra
KC4ZGP
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Posts: 725




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« Reply #6 on: July 06, 2017, 09:23:09 AM »


The watts from the generator are different watts than from your radio.

No?

OK.

So my idea is this, do what W9IQ suggests.

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W8JX
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Posts: 11802




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« Reply #7 on: July 06, 2017, 10:11:44 AM »


The watts from the generator are different watts than from your radio.

No?


Well kinda but you have to factor in power supply efficiency and power supply start surge too.
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Ham since 1969....  Old School 20 WPM Extra
KC4ZGP
Member

Posts: 725




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« Reply #8 on: July 06, 2017, 11:14:07 AM »

I was aping a guy I knew way back who claimed the voltage from the telephone DCO
is different than what my 600 ohm VF channels needed.

I said uh-huh as I slowly closed the door to the facility. Wow!

Herr Fuchs explained to him otherwise.

Herr Fuchs didn't speak English.

Kraus



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