not too scientifically i cured a noisy gen i read some articles i
think in qst about a ham that tried to do same w/a noisy car

i took rfshielding tape around all the wires made a 'rf' proof can to
shield stuff i thought would radiate super grounded everything
properly including the gen frame and i also made some rfabsorbing
sheetmetal like plates to cover the gen execpt for air/exaust which
had a little copper screen hinged door flap the shielding was mostly
scrap so it didn't cost much and kept the basic weight and size of the
gen same since it had a pipe like frame and the shielding i hung inside
that

you can try to see if there is a particular 'thing' in the gen that
radiates , spark plug? it's cable? the inverter? if it's mostly one
item perhaps you can just shield that/??

best of luck

In article m,
Straydog wrote:

On Wed, 19 Sep 2007, Fred McKenzie wrote:

Ignition noise is not the only way a generator can interfere with radio
reception.

A Honda "inverter" generator was used at this year's Field Day, but it
caused a broad-band noise on the HF bands. Locating the generator as
far as possible from antennas helped.

An inverter generator produces 3-phase AC power, rectifies it and drives
a DC-to-AC inverter that produces 60 Hz power. Result is a
lighter-weight generator, and greater efficiency can be achieved by
reducing engine speed when less power is used. Honda's also have
extremely low acoustic noise levels.

A call from the Honda dealer to Honda Technical Support received a reply
that you have to use a LONG extension cord because inverters generate
radio interference! I have since used a portable AM/Short-wave radio to
check the Honda generator as well as one from Yamaha. Both wiped-out
reception up to the 18 MHz range of the radio, when the radio was within
several feet of the generator.

Does anyone have experience cleaning-up the interference from the
inverter in one of these generators?

Fred
K4DII


I don't know, but short of a lot of filtering (and figure X db power
losses from the filter) and sheilding might help.

I was annoyed by these lightweight inverters that are basically souped up
switching power suplies (even the ones in computers are cleaner), but I
finally bought an old dynamotor from Fair Radio Sales (Lima, Ohio) that
ran 24 volts in (two deep cycle marine batteries in series, here) and
nameplate output is 117 VAC at 60 cps, max 300+ watts continuous duty and
about 600 watts input, DC at 24 v, and 25 amps. It is very very clean and
I can hook up radios and just about hear no RF noise. It even runs at 12
vdc input and reduced output voltage, maybe 50-60 volts ac, but sounds
like a lower speed, too, so maybe like 40 cycles per second.

If you get one (they are about $75 now), you need to spin the commutator a
few times to wipe off the copper oxide build up, then it takes off like it
should.

So, if you have 90-95% efficiency in a inverter-generator, and build a RF
filter that causes--assuming--3 db insertion loss, you're ending up at 50%
efficiency anyway and you still have to worry about resonances,
impedances, power handling, inductances, capacitances, etc.

Your other option is just run all solid state gear off batteries (and
solar cells?) if you want no noise and simplicity.