Hello Shopbot friends:

Having worked as an electronics engineer in new product development for many years, it must be understood that any electronics with switching circuitry, (anything from SCR based light dimmer switches, to PCs with high clocked CPU boards and switching power supplies, generate intense broad spectrum electromagnetic radiation that if unshielded, would wipe out radio communications within the confines of a house. That reality is what resulted in the FCC creating standards that if followed, will minimize the interference of the aforementioned devices with near range RF communications. Open any modern electronics, and you will see tightly sealed metal, well grounded enclosures, with small (in RF terms) openings, little bypass capacitors, ferrite beads, line filters, and other tools of the trade that manage when correctly applied, to suppress and contain RF emissions, and thusly not wreak havoc with your radio reception.

If I take the side of my PC case off, I can't use my AM radio that sits near by. Put the cover on, and then the radio is fine.

My point with having worked in this area, is that any such digital/noisy electronic product must get FCC approval by a certified laboratory. I have worked on products, that when they are tested, go into an RF anechoic chamber, with big arrays of antennas aimed at the device under test. In the broad spectrum sweeps which are conducted, if the limits of emitted RF emissions are exceeded at any frequency, everything stops, and electronic band-aids are applied, wires moved, capacitors added, ground planes reworked, grounding within the chassis gets altered, until the limits are no longer exceeded. I have made changes in the past, which I know, had one wire moved a little, we would have failed the test.

So look inside of your Shopbot at all the wires, the fancy shielded, well grounded box, and realize that someone had to work like mad to get that unit to pass. And if someone made a prototype pass at an FCC test lab, who's to say that some small production change in the next batch of products, didn't just toss that careful little RF band-aid out the window.

I wouldn't personally worry at all about where the RF is getting out,,,,,,,, it could be anywhere, and to exactly figure out where the RF was escaping (through the USB cable, or the power cable, or the motor driver wires etc), and further how to stop it, could cost thousands. It is what it is.

In my house, the worst source of interference with my AM radio reception, comes from my old time SCR based light dimmers. I know at night if I put some lights on the low setting, I can forget about listening to AM radio. And I don't even think of having my radio on if I am going to turn on my Bot, I'm fine with that. (Or listen to an FM radio, the genius invention of Major Armstrong, that doesn't pick-up stray spurious electronic emissions and attempt to "demodulate" them along with your favorite radio program............ Chuck