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

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.

On Sep 19, 7:19 pm, 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

How about a shielded enclosure. Attention would have to be given to
routing the exhaust and heat from the enclosure. Just a thought...
www.telstar-electronics.com

Telstar Electronics wrote:
On Sep 19, 7:19 pm, Fred McKenzie wrote:

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


How about a shielded enclosure. Attention would have to be given to
routing the exhaust and heat from the enclosure. Just a thought...
www.telstar-electronics.com

Not only exhaust, heat and fresh air for combustion, you'll need to
bypass/lowpass any electrical conductor going in or out of the
enclosure, and those cheap clip on ferrites won't do much good, you need
pi networks on the conductor itself. You might start with the inverter
section of the generator, make sure it's in a well sealed (electrically)
enclosure, bypass/lowpass the conductors coming out of it and as long as
you don't cause problems with circuit cooling put some RF absorber
inside the enclosure, if it gets absorbed inside it won't get out, and
don't be dissuaded by the absorber specs, they work quite well in the HF
range. You can also get free samples.

http://www.specemc.com/emipower.asp
http://www.cumingmw.com/micro_rf_pc.html
http://www.eccosorb.com/pages/89/Product+Index

Been there, Good luck,
W8LNA

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

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.