Electronic noise

[David Reed]

I just purchased the Jet 1642 lathe with the electronic VF speed controller. I love it, but my wife listens to AM radio a lot and it creates havoc with the extreme noise levels. What type electronic filters do you use to limit this feeding into the electrical system?
Thanks
David

[Paul Atkins]

Tell her to listen to NPR on FM. Actually, maybe an external antenna for the radio away from your shop.

[Kyle Iwamoto]

Use hearing protection so you don't hear her.:eek:

This has been discuissed before, I don't think there was a final resolution to the problem...... Move the radio, don't use AM, external antenna, all were mentioned. I personally would try the external antenna.

[Ken Fitzgerald]

David,

I don't have your lathe so I can't experiment. I've been working in electronics since 1969. I've worked on everything from UHF, VHF and HF transmitters and receivers, to X-band radar and S-band radar used in air traffic control to MR scanners and CAT scanners and x-ray equipmient.

The 3-phase inverter on my lathe is a separate box on the back of the lathe. You can't reduce airflow to the inverter/controller as the air flow is needed for cooling.

A simple electronic shield of some sort around the controller would probably help. The shield would need to be grounded to the lathe itself.

If you look at the door of a microwave over, the "screen wire" you are looking through behind the glass is an electronic shield to prevent RF radiation from escaping through the window of the door.

The holes in the screen wire/shield are sized to effectively appear as an electronic short or solid piece of metal and thus the RF doesn't leak.

You could try using some metal screen wire if you can find some and fashion a screen/shield around your 3-phase inverter/vs controller. Make sure you ground it well to the lathe body. Scratch any paint off and make a good metal to metal connection even if you are just attaching one end of a copper wire to the screeen and the other end under a screw. Remove any paint or coatings....a good ground on the shield is important.

Temporarily you could try using a piece of aluminum foil and fashion a shield and ground it and enclose your inverter/vs controller...just to see if it helps. Make vent holes in the top and bottom of the shield so air can flow and cool your inverter/vs controller. If that temporary one eliminates or minimizes the problem, then you can worry about a more permanent shield.

[Ken Fitzgerald]

David,

It is possible that the electronic noise is traveling through the AC wiring in your shop and house.

In that case you would need to find a RF filter. I am sure some are made that you could plut the radio into it and then it plugs into the wall outlet. I'll see if I can find something.

[Skip Spaulding]

Talk to "Radio Shack" they may help and you might try running your power cord through sealtight or greenfield, like Ken said it needs to be grounded.

[Bill Davis]

As noted in other posts interference is caused in two ways - conducted, and radiated. To solve the problem you need to determine if it is one or the other or both in your particular case. If it is primarily conducted interference a filter on the power cord to the lathe should result in a significant reduction of the 'noise' in your AM radio. If the interference is primarily radiated, the lathe is acting like a transmitting antenna. To reduce that the transmitted noise must be contained by shielding. If the 'noise' is a result of both then a combination of both must be done to acheive significant results.

All that being said, other solutions have been mentioned such as switching to FM. Trouble with that is that FM stations do not offer the same programming as AM and so is not a likely solution, and switching to NPR - YUCK! A suggested solution that does have merit IMO is to (in my words not the original suggester) increase the desired signal at the receiver so that it can overcome the undesired noise signal. This can be done in a variety of ways. First I would try re-orienting the AM radio receiving antenna to maximize the radio station signal. As it gets stronger the noise will be reduced so you can get immediate feedback of success. An external antenna on the radio may help or actually make it worse.

In short, you have to experiment to find what gives you positive results. Don't bother with the YUCK experiment.

[Mike Lipke]

Do a search for Oneway RF filter.
You can buy them from Oneway, but there was a thread a while back on where to get the same thing for (I think) around $15.

[Mike Lipke]

OneWay sells this for $59.

Do a search on Google for a Corcom 10VR6.
$23

OneWay's website has downloadable instructions on how to wire it.
If you feel guilty, buy it from OneWay.

Inverters are inverters. Should do the job.

[Terry Achey]

what's AM ? :D

[David Reed]

Thanks for the input. I had already tried constructing a Faraday cage of bronze screening and found limited success, but a some. That's why I was looking for a line filter. I will try the Corcom filter. I assume that this is wired into the 120 line (input). The filter is rated for up to 10 Amps. My input range on the inverter is up to 18 but the motor is rated for 4.5 (230v). Is this large enough or, due to internal losses, does the inverter draw more than 10? Guess I could load it up with am ammeter in line. Can I install the filter in the receptacle to which I plug the lathe or does it need to be nearer the source (inverter)? I had a similar problem with my Ham radio on my sailboat but merely turn off the inverter when using the Ham which instantly and perfectly solves the problem.
I do occasionally listen to FM (including NPR) but at the risk of starting a political firestorm, I will not divulge my preferences or why I sometimes switch hit.
David

[Ken Fitzgerald]

I do occasionally listen to FM (including NPR) but at the risk of starting a political firestorm, I will not divulge my preferences or why I sometimes switch hit.
David

Uh Oh! A switch hitting NPRer!:rolleyes:

David,

I'm not familiar with the filter. If you have the means, I'd measure the current on the 120 vac line while you have the lathe loaded. Then you should be able to determine if the filter will handle the current. Good luck! These things can be a real problem to solve.

I am fighting one on an MR scanner right now and most likely will be leak in the room shield or.....a bad ground allowing a wire coming into the room to be an antenna of sorts.

[Dick Strauss]

Dave,
10A on a 110V line will not be enough to supply the 1.5hp to your lathe. You'd need a minimum of 15A rating on the device before you should consider it (20A would be better)

You might want to look into a good heavy duty power strip. The strips are not only designed to block lightning strikes (surge suppresion), they also have noise suppression circuitry built into the units.

They also make line suppressors that are little more than an iron cylinder that clamps onto the line to capture RFI.

[Mike Lipke]

Oneway puts that Corcom filter on their 3hp lathes.

[Mike Lipke]

Here is Corcom's phone #
1-800-468-2023
Corcom #10VR6 is what OneWay uses for all their lathes, some are pretty darn big, 3hp, 25 amperes.

Here is the link for the Spec sheet:
http://www.cor.com/Series/PowerLine/R/

Here is where you can download the wiring diagram. It goes between their magnetic switch and the VFR, I believe. You don't have a mag switch on your Jet, so it would go in series between the power cord and the VFR:
http://http://www.oneway.ca/lathes/2436_access.htm (http://http//www.oneway.ca/lathes/2436_access.htm)

Good luck