RF interference

[dannyshamoon]

I get a lot static (like a duck quacking) from my PP on my AM radio. Is there a filter I can run between the outlet and the motor to take care of this?
Thanks for the help.
Danny

[RFGuy]

I don't own a PowerPro, so I have no direct experience with it. However, I do know that these self reluctance motors are known to produce vibration and acoustic noise on their own (viewtopic.php?p=265716#p265716). So, you may want to confirm that the noise is coming out of the AM radio and not from the PowerPro directly. You said "static", so I would assume the static is coming from the AM radio, which is likely an EMI issue. I would start by trying a ferrite choke on the AC power cord to your AM radio. If this doesn't work, there are CL/LC EMI filters that can be inserted inline to provide additional filtering. A good primer on EMI can be found here if you want to know more about it (https://incompliancemag.com/article/a-b ... onnectors/). Lastly, this may/may not solve your problem. As Jack posted back in 2015 (viewtopic.php?p=194898#p194898), he had AM radio interference from his PowerPro and it didn't go away even when he powered his AM radio from a battery instead of AC power. So, input filtering of the AM radio may not solve this issue since Jack ran his radio from a battery and still had interference issues according to that post. My theory for why he may have still had issues is that I suspect the PowerPro design has insufficient power supply filtering on both the input and output of the power supply. As a result, power supply harmonics can backfeed into the 120V power line. IF this happens then all of your house wiring becomes a big antenna and the AM radio will easily pick this up.

Hopefully one of the forum members that owns a PowerPro and who has dealt with radio interference can give you some pointers here. Also, you may want to contact Shopsmith directly to see if they have any tips for this as well.

[Hobbyman2]

be sure to check all of your grounds in the electrical system, I have LED lights in the garage and they make a lot of static in my HAM radios .

[wa2crk]

There is considerable RF noise coming from the Power Pro. I noticed it when I pulled my car into the garage with the AM radio on. I had a pulsing raspy sounding noise. When I unplugged the PP the noise stopped immediately. I was not able to determine if the noise was coming from the display or not. Not really affecting me because I don't listen to AM radio at all.
Bill V

[dannyshamoon]

I should have mentioned that the noise in radio is with the PP NOT RUNNING, just on. The LED lights in my garage appear not to give off any RF/EMI because there is no radio noise with the PP unplugged.
Thanks for the replies
Danny

[dannyshamoon]

There is considerable RF noise coming from the Power Pro. I noticed it when I pulled my car into the garage with the AM radio on. I had a pulsing raspy sounding noise. When I unplugged the PP the noise stopped immediately. I was not able to determine if the noise was coming from the display or not. Not really affecting me because I don't listen to AM radio at all.
Bill V

YES, this is the same experience I 'm having.
Danny

[jsburger]

I should have mentioned that the noise in radio is with the PP NOT RUNNING, just on. The LED lights in my garage appear not to give off any RF/EMI because there is no radio noise with the PP unplugged.
Thanks for the replies
Danny

It is the switching power supply. That is powered up even if the PP is not running. There should be no interference if the main head stock is turned off via the toggle switch. Not just the Off button on the control panel.

[dannyshamoon]

I should have mentioned that the noise in radio is with the PP NOT RUNNING, just on. The LED lights in my garage appear not to give off any RF/EMI because there is no radio noise with the PP unplugged.
Thanks for the replies
Danny

It is the switching power supply. That is powered up even if the PP is not running. There should be no interference if the main head stock is turned off via the toggle switch. Not just the Off button on the control panel.

Yes it's just when I turn the On/Off switch on that I get the noise, so it's only powering the console. Turn the headstock off, no noise. My guess it is the electronic control for the motor.
Danny

[claimdude]

I get the static as well. I use a Makita jobsite radio and listen to AM. I attached a piece of thin aluminum wire to my antenna and ran it up the wall until the static disappeared. Problem solved ;-)

Jack

[RFGuy]

Okay, I am resurrecting this thread because I think I found some useful information. On both this thread but others in the past, I have seen mention of a few Shopsmith owners who have had trouble with AM radio interference when the PowerPro is plugged in. I found one relevant section on Teknatool's website related to this that I thought I would post here so that it might help PowerPro owners. As a reminder, the PowerPro uses a switched reluctance motor (DVR) that was invented by a company called StriaTech. They sell their motors to the woodworking community through Teknatool (Nova is a brand underneath Teknatool). So, why am I posting Teknatool info here on a Shopsmith site? The internals are going to be very similar between a Teknatool DVR and Shopsmith PowerPro, not identical, but very similar, so I believe this info could be of value to Shopsmith PowerPro owners. There is a write-up below from one of the Teknatool technical experts on this subject and they also recommend a particular surge protector to use to mitigate any interference. NOTE: The PowerPro doesn't have the diagnostic LED's mentioned below but the rest should apply for the PowerPro if you are having AM radio (EMI) interference. Hope this helps.

Excerpt #1 from Teknatool on AM radio interference/EMI:
If you are experiencing AM radio interference due to the Electromagnetic Interference (EMI) emitted from your DVR machine, an in-line EMI filter will likely solve your problem. The following is a surge protector with built-in EMI filter which DVR customers and technicians have had success with installing.

https://www.tripplite.com/protect-it-6- ... oules~TR6/

In the description of this product it states;
3 diagnostic LEDs indicate AC present, line fault & protection present
EMI/RFI noise filtering

The following is from one of our DVR electrical experts, Mike Swerbensky, with a deeper explanation of the problem and the solution:

"I have used these for the same symptoms you are describing and including ham radio, (AM), interference. I still use them today and most work great. I have tested them on AM radio by dialing in the interference and then employing the EMI/RFI filtering systems,( repeatedly.)That is plural because not only do I use a tripp lite surge protector daily, ( isobar 4 ), we have our own filter that performs very well. As to whether or not the product works for EMI/RFI isn't always indicated by the name of the product but rather the specifications of that product. If what you are using doesn't work then maybe a better filtering/conditioning product should be obtained. Years of testing this type of interference has taught me that many conditions come into play, such as the environment around us. Humidity, barometric pressure, objects and reflectivity all play a role. Always verify that the machines ground is intact and that your electrical service is grounded properly."