[Milsurplus] Gilbert MRCA Event AAR - MEP-025 noise

[David Olean]

Be glad you don't have a Detroit Diesel 2-71 genset. I have a 30 KW 
military unit. a PU-708G Marine Corps genset. It runs at 1800 RPM but 
the air blower runs at a very high speed and sounds like a 707 taking 
off in your backyard. The first weekend I ran it, the neighbors 600 ft 
away complained. We could not sleep anywhere near it. The next year, we 
built a building around it. That knocked down the noise, but it was 
still loud. It is not running now. It needs an overhaul.  I do not miss 
the noise. That high speed blower really whined out! It sure made good 
power though. Solid 60 Hz all the time and voltage fluctuations were 
about a volt or two from no load to full load. It ran 208 3 phase .

Dave K1WHS

On 9/30/2019 6:23 PM, Kenneth G. Gordon wrote:
> On 30 Sep 2019 at 17:34, Ray Fantini wrote:
>
>>      Noise suppression for the MEP-025, the generator has a fifty foot cable that connects it to the
>>      slave connector on the mutt. But the generator itself is so noisy (acoustic not electrical) that it is
>>      annoying.
> Ray:
>
> First of all the MEP-025 is a 3600 RPM generator, and that alone makes for lots of noise. If
> it turned at half that RPM it would make a big difference, but you can't change that.
>
> Secondly, most of the noise from small generators comes from mechanical engine noise,
> valve clatter, and such, and very little from the exhaust. Adding an easily removeable
> car-muffler can modify the exhaust noise, making it less "sharp" but doesn't really quiet it
> much.
>
> The only real way to quiet such a generator is pretty much as the manual says: "bury" it. At
> a recent field day, we stuck my small 2200 watt genny down in the bottom of a nearby ditch
> and that made a huge difference on apparent noise from it.
>
> Some of us have had some success building a sound-proofed box around our generators
> with the top open so that the noise goes pretty much straight up into the air rather than
> "sideways", but even that is kind of a PITA to do.
>
> You might consider using a pair of series connected HUGE batteries like are used in diesel
> trucks or large busses. I don't know what is the  24-28 VDC load you have, but a pair of
> those MIGHT suffice. At least you could charge them periodically from the MEP-025 rather
> than having to have the genny running continuously.
>
> The batteries I am thinking of usually weigh near 100 lbs each, and are 18" to  24" long, a
> foot high, and 12" to 18" wide or so.
>
> Ken W7EKB
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