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Author Topic: 3kva inverter for mobile usage  (Read 8052 times)
TF3CY
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Posts: 20




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« on: July 03, 2016, 07:21:58 AM »

Hi - I'm doing work on my small wan and I plan to be able to do to QRO operating from the wan

Is thee a general consensus on a good brand of inverters that give acceptable level of RFI?

I plan to use my KW linear for 6m and 2m for EME/MS work and then some HF work also.

73, Benni TF3CY
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VK3BL
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« Reply #1 on: July 04, 2016, 01:11:46 AM »

Hi - I'm doing work on my small wan and I plan to be able to do to QRO operating from the wan

Is thee a general consensus on a good brand of inverters that give acceptable level of RFI?

I plan to use my KW linear for 6m and 2m for EME/MS work and then some HF work also.

73, Benni TF3CY

Hmmm,

Off the top of my head I'd just say make sure you don't get a 'modified sine' aka unfiltered square wave inverter.


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J.D. Mitchell BA  - VK3BL / XU7AGA - https://www.youtube.com/ratemyradio
N7BMW
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Posts: 207




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« Reply #2 on: July 04, 2016, 09:56:48 PM »

Hi - I'm doing work on my small wan and I plan to be able to do to QRO operating from the wan

Is thee a general consensus on a good brand of inverters that give acceptable level of RFI?

I plan to use my KW linear for 6m and 2m for EME/MS work and then some HF work also.

73, Benni TF3CY

I hope you realize that a 3kw inverter operating at 80% efficiency requires 300 amps input.  Not only do you need the inverter, you need a battery bank and a way to charge the battery bank to supply that much power for any sustained amount of time.  Only short transmissions are practical at that power evel.
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KH6AQ
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« Reply #3 on: July 05, 2016, 04:41:24 AM »

I have never found an RFI quiet DC/AC inverter. I did quiet down a 200 watt inverter by installing homebrewed input and output EMI filters and putting the inverter inside an EMI tight metal box. The DC filter is designed for 30 dB of normal-mode attenuation at 3.5 MHz and the output filter is designed for 30 dB of normal and common-mode attenuation at 3.5 MHz.

For a 3 kW inverter I would homebrew the input filter and use an off-the-shelf AC filter on the output. For the DC input filter I'd series-parallel 16 EATON HC3-R50-R inductors to make a 500 nH inductor rated for 312 amps. They are 500 nH, 78 A inductors. On each side, with short leads, and routed opposite each other, (for zero magnetic coupling), two 0.22 uF ceramic capacitors to ground are placed. With each capacitor being 2 cm long from the inductor to the enclosure wall (place it right where the DC power enters) the attenuation is over 37 dB (6 S-units) at 3.5 MHz. A suitable capacitor is the AVX AR205C224K4R. Above the SRF of the capacitors the filter is an L-L filter having 500 nH series and 7.5 nH shunt inductance to form a 37 dB filter. The capacitors on the inverter side of the filter may add attenuation, depending on the noise source impedance.

This filter meets the Middlebrook criterion to 13 kHz. If the power supply loop bandwidth approaches this it could become unstable.
« Last Edit: July 05, 2016, 09:39:14 AM by WX7G » Logged
W9IQ
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Posts: 1845




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« Reply #4 on: July 05, 2016, 04:42:12 AM »

You may wish to consider adding an AC generator to the vehicle's engine. Something like this from a source close to you:

http://www.fabcopower.com/generat/bgen.htm

- Glenn W9IQ
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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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« Reply #5 on: July 06, 2016, 06:35:10 AM »

I hope you realize that a 3kw inverter operating at 80% efficiency requires 300 amps input.  Not only do you need the inverter, you need a battery bank and a way to charge the battery bank to supply that much power for any sustained amount of time.  Only short transmissions are practical at that power evel.

While this is mostly true, it would only see full load key down CW or tuning as average load will be much less or about 1/2 that at most running SSB. Also with engine idling you can produce 60 amps or more charging rate so you are not completely on battery power As far as a battery "bank" to power it it is not needed but you do want a second battery in parallel with main battery or two extra batteries in parallel if you do not want to directly use main battery).

While I have not done this I have used electrically powered hydraulic systems for snow plows for well over 20 years that can draw 200 amps and more (the colder it is, ie thicker the oil, the more power it draws) and I have done fine with dual batteries and stock alternators because your duty cycle at full load is never even close to 100% and batteries have a chance to recover. First few years I did this I used a single battery and battery was shot after one year from load cycles while with dual batteries I get near normal life cycles.  
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Ham since 1969....  Old School 20wpm REAL Extra Class..
TF3CY
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Posts: 20




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« Reply #6 on: July 14, 2016, 01:52:56 PM »

I have been going over this - And after reading this: http://ludens.cl/Electron/chinverter/chinverter.html

and some reviews on Ebay - I'm still very reluctant to buy a chinverter Wink

This could potentially be a $400 waste of money

So, i know someone that has a chinverter - going to test that one

I work fora Telco, they use 48v extensively  so I got two 160Ah batteries - could probably get more.
 Plan was to use a small 500W generator to charge the batteries - when used for long periods, but I could probably run SSB of the two batteries for some time.. for MS/EME I would always need a supply as those are high duty cycle modes that require about 1500W input
 
I will post any findings

been looking at these:

http://www.ebay.co.uk/itm/3000W-Power-Inverter-Pure-Sine-Wave-AC-Converter-Watt-Inverter-Solar-Inverter/152144839495?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D35377%26meid%3D91051691fc6841809bd716fc0cf007f4%26pid%3D100033%26rk%3D2%26rkt%3D8%26sd%3D390464463107

and

http://www.ebay.co.uk/itm/3500W-Car-Power-Inverter-Pure-Sine-Wave-Inverter-12-24-48VDC-to-220V-AC-LED-/201432055991?hash=item2ee64940b7:g:cg4AAOSwu4BVuFWG


73, Benni
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WA7AQH
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Posts: 0




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« Reply #7 on: July 14, 2016, 04:25:42 PM »

Look at Magnum or Xantrax for inverters. Magnum would be my first choice. As someone else noted, make sure it's a true sine wave inverter; most of the Chinese ones you see or on Ebay are modified sine wave. They'll not only give you a lot of noise, they'll fry some equipment.

We've got a Xantrax in our motorhome, and it gives me a reasonable noise floor on 2m FM as long as I put chokes on the power line to the radio and aren't running anything else noisy (like the microwave). Obviously SSB could be different.
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