FM Radio Static while using generator

jrkowalski wrote:
When I run my portable generator while using my FM Stereo it produces a lot of static. I was careful to purchase a generator that produces power <5% THD so as to avoid this. Is there something I can do to prevent the static?

I'm assuming that this is an inverter type generator. It's very unlikely the problem is coming to through the power lines, more likely it's radiated from the switching electronics and so probably not much simple that could be done.

You can confirm if its coming to through the A.C. power line by borrowing a good powerline filter like sold for audio equipment. If that makes no difference when added then the problem is radiated.

Some tin foil or a metal plate connected to the ground put near the electronics of the generator as a shield may help, but it's a long shot.

Is the FM stereo connected to the 12 volt DC system or the 120 volt AC system?

Spark plug voltage radiation. Fine screen tent over entire ignition circuit then connect with wire to a nail then push nail into earth. Aluminum screen works fine and you only need to shield the ignition not the entire generator.

Perhaps an inverter is in your future. I hope you're not running a gen strictly for the radio.

When I run it using 12 volt or connected to 120V line plugged into my house, it is crystal clear. When I'm connected to the generator, even when it is at the end of my shore line (approx. 20' away) I get the static. I bought a ground rod & wire for my generator but haven't used it yet, is that what you are suggesting, mexicowanderer?

horton333 wrote:

jrkowalski wrote:
When I run my portable generator while using my FM Stereo it produces a lot of static. I was careful to purchase a generator that produces power <5% THD so as to avoid this. Is there something I can do to prevent the static?

I'm assuming that this is an inverter type generator. It's very unlikely the problem is coming to through the power lines, more likely it's radiated from the switching electronics and so probably not much simple that could be done.

You can confirm if its coming to through the A.C. power line by borrowing a good powerline filter like sold for audio equipment. If that makes no difference when added then the problem is radiated.

Some tin foil or a metal plate connected to the ground put near the electronics of the generator as a shield may help, but it's a long shot.

Static the OP is talking about is most likely not due to "inverter" or even a standard non inverter generator head but due to the engines ignition system.

For any RFI you need to isolate the SOURCE of the noise by moving the SOURCE further away from the radio device.

In other words, don't park the generator close to the RV or on the side of the radio.

Most ignition noise will be more noticeable with WEAK stations, try a stronger station.. AM is more susceptible to RFI noise than FM, if listening to AM not much is going to help, just the nature of the beast.

Typically ignition noise in vehicles are suppressed by using resistor plugs and plug wires.. Not much options for a generator, not like you are going to change the plug wires (coil and wire are molded together) and not a lot of resistor plugs available for small engines..

It actually is NOT an inverter generator. My shore line connection is in the back of my 26' trailer and I ran the line out it's full length to get it away from the trailer. The station comes in strong & clear when running on battery power, but as soon as the generator is running, it is all static.

I didn't buy it just to run the radio, but would like to listen to it when the generator is running. I suspect I would get similar results from the TV or DVD player?

My last trailer had an onboard generator & I never experienced any issues with static for any of the audio/visual.

No. It takes a cage. A fine screen conductive cage that acts as an absorbing antenna. An engine ignition can emit tens of watts of signal. Bad enough. But not only radio frequencies but intermediate frequencies that are picked up by the chassis of the radio. Try this. Buy aluminum bug screen make a tent overtop the generator but the screen must have an earthing ground. Wire clip, wire and spike. Did that help? Some radios are a LOT more sensitive than others.

And don't feel bad. Noise suppression is an art form and HAM operator forums are kften busy dealing with it. "Hamsters" are also quite talented.

Ok Mexicowanderer, getting closer to understanding. When you say "Tent" I am envisioning a free standing aluminum bug screen tent that the generator sits under, is that what you are talking about?

jrkowalski wrote:
It actually is NOT an inverter generator. My shore line connection is in the back of my 26' trailer and I ran the line out it's full length to get it away from the trailer. The station comes in strong & clear when running on battery power, but as soon as the generator is running, it is all static.

I didn't buy it just to run the radio, but would like to listen to it when the generator is running. I suspect I would get similar results from the TV or DVD player?

My last trailer had an onboard generator & I never experienced any issues with static for any of the audio/visual.

So it is radiated interference, which is much harder to fix. The metal 'tent' suggested can always work, but it's awkward and can be harder to make effective than it first seems (you may even have to drive a ground stake, awkward for a mobile vehicle).
As your's is not an inverter generator that radiated noise pretty much has to be the spark circuit radiating. By regulation they are supposed to have suppression of the noise, shielding or resistance. As others are suggesting you are going to have to improve that suppression. The easiest way is to add resistance to the high voltage line; if there is none now. This can be built into the plug or into the wire. You can buy resistive plug wire and cut to size and you can also buy a bulk resistor that will fit at the plug (or perhaps find a resistive plug that fits) and the choice depends on how long the wire is (longer wire has more resistance, more is better for reducing noise till there is too much and the motor does not work as well from lack of spark).
Did you by any chance change the spark plug, you may have switched to a non-restive plug. Another thing is if there is a shield over the wire make sure it is still connected to the metal frame, if it came loose then it will make things worse not better.
Good luck, these problems can be a pain to track down.