On Wed, 19 Sep 2007 20:19:37 -0400, 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,

I have an EU2000 that I use for charging the batteries in my 5th wheel
trailer. I have limited experience with operating the radio equipment
from this "QTH" but here is what I have observed.

First I found that the major noise source was the switch-mode battery
charger built into the trailer. In fact the original one acually
interferred with home OTA TV while the trailer was parked beside my
house! I replaced it with an IOTA unit that supposedly meets FCC
requirements but is still a noise source.

I finally built an analog "smart charger" using an Astron PS for the
raw DC and pass transistors and a UC3906 IC.

Once this was cleaned up I could hear the noise from the Honda. I
should back up and say that in my earlier attempts to clean up the
charger noise I determined that a lot of it was conducted on the AC
side, so I had previously installed an industrial grade brute force
line filter at the trailer's AC distribution panel.

So from that respect, the AC side is pretty well filtered, although
the filter isn't necessarily installed in an optimum location. But I
don't think this matters because my further experience is that most of
the remaining noise is radiated.

Shielding is of course out of the question as a practical matter. This
leaves the physical separation between the generator and the antenna
as the best remedy.

I also operate Field Day from home in Class 1E. The Honda sits right
outside the shack and powers the Astron PS that runs the radio. I
float a deep cycle battery across the 13.8 V. The generator runs in
Econo throttle mode and runs for hours like this. I'm hard put to
even know that it's run out of gas unless I keep my eye on the battery
voltage.

I mostly run only 20-meters and the antenna is a 3-element beam
located about 100' away. Even pointing at the shack I cannot hear any
RFI from the generator. When I slip down to 40 or 80-meters any RFI
is buried in atmospheric noise.

So I think Honda is right; get a long extension cord and move the
generator away from the antenna.

Regards,

Wes N7WS