[RFI] Aims 5000 Watt MSW Power Inverter

dgsvetan at rockwellcollins.com dgsvetan at rockwellcollins.com
Mon Sep 15 13:08:32 EDT 2008


That's one monster of a converter!  Doc, since you periodically mention 
various inverters and power supplies in your posts, I presume that you 
have need for such devices.  When considering such devices, keep in mind 
the following:

1.  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 hope you 
have a battery and charging system that can handle that.  (I read some of 
the review comments at the web site where your link leads to and laughed 
my self silly about guys toasting their vehicle alternators.  I think they 
were a little short-sighted in being able to handle the beast.)

2.  The device produces a modified sine wave output and weighs only 21 
pounds for a 5 kW device.  Those two facts tell me that the heart of the 
beast is a high frequency inverter in which a 60 Hz sine wave is 
synthesized so that they do not have to use any 60 Hz magnetics.  If they 
did, the weight would be hundreds of pounds for a 5000 watt unit.  You can 
be sure that there is a LOT of hash flying around from this thing, 
probably on both the input and output connections. 

3.  They mention EMI, but make no statement about conforming to any 
specific standard.  Note that concrete drills and other construction tools 
don't care much about hash on their power cords.

I've said this before, and I'll say it again:  do NOT buy or attempt to 
use power supplies and power inverters that are not designed expressly for 
communications applications unless you are prepared to tackle the fix 
yourself.  I saw that this device sells for nearly $600.  My guess is that 
you'll need several hundred dollars more to spend on the filtering, 
especially for the input side.  It can be a challenge making inductors for 
a filter when you are working with welding cable!  The alternative is to 
locate this monster well away from any 160m or HF antennas so that its 
racket doesn't drive you nuts.  I would guess that 50 feet would be a good 
start, and you might need to go further than that.  You would probably 
have to filter the 120V output just to keep from polluting your shack and 
home woth noisy power.

Quite frankly, I'd suggest a modern 5000 watt engine-driven alternator as 
a better bet for this power level.  Cost is about the same and alternator 
power is clean.  Most gen sets these days have noise suppressed ignition 

On a related topic, I happened to be looking on eHam the other day at some 
product reviews on switching power supplies for amateur radio use.  It is 
a sad thing to say, but some manufacturers just have to shave corners in 
anyway they can and thus put the hurt on any buyers who don't pay minute 
attention to detail when making a buy.  There appears to be at least one 
brand of switcher out there (and no, it is not Astron or MFJ) that is 
meant for communication applications, but is NOT friendly for HF use!  The 
manufacturer seems to think that most buyers are running VHF and above 
rigs, so the hash that is generated by the switcher is not well-suppressed 
within the unit.  One buyer spent several dollars adding filtering to make 
his unit usable with his HF radios.

I have no connection whatever with Astron, but my SS-30M continues to 
power my HF and VHF/UHF gear just fine with no issues.  It also did very 
well in ARRL lab tests in 2002.  There are others that are nearly as good 
for noise suppression, but none I have seen that are any better.  I use 
that switcher both at home and at Field Day.  In FD use, the antennas are 
right above (or otherwise close) to the power supply and no problems.  Go 
to the ARRL web site and assuming that you are a member, you can check out 
the League's product test of the Astron and several others switchers. 
Check it out - good reading!

73, Dale


kd4e <doc at kd4e.com> 
Sent by: rfi-bounces at contesting.com
09/14/2008 08:46 PM
Please respond to
doc at kd4e.com

RFI List <rfi at contesting.com>, "tvi-rfi-emi at mailman.qth.net" 
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[RFI] Aims 5000 Watt MSW Power Inverter

Anyone have any experience with this inverter, please?

Aims 5000 Watt MSW Power Inverter:


Thanks! & 73, doc, KD4E
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