[BC] Fact or wives tale? AM RF interference on computers.

[RichardBJohnson at comcast.net]

Of course keyboards are not designed to operate in 25 V/m fields, but most would probably run okay. They use a serial link that runs about 120 kb/s. USB keyboards run at the megahertz speeds, but they probably will work at AM transmitter sites. What may be a problem are high-power FM and TV. These VHF and UHF frequency components, once they get into a keyboard or computer may simply overload everything and anything because their resonances are not well loaded (damped).

Getting something near a "screen" that causes strange characters is definitely a tale created by somebody who doesn't know how they work! The characters are not generated anywhere near the screen. RF being introduced into the screen could cause pixels to brighten or dim. It could even cause them to burn out! However, you don't alter characters or even create new ones that way. You would need to upset either the character generator that is built into the screen-card or screen memory (the screen regen buffer), also in the screen card. Since the output of the screen-card is buffered with powerful analog or digital amplifiers (buffers), designed to drive low-z loads at hundreds of megahertz (the pixel frequency) I seriously doubt that any RF is going to be coupled back to anything in the card.

One could certainly test samples to see if everything worked okay. I’d place my money on everything working fine at AM sites, but some stuff being problematical near FM antennas. Of course those external amplified speakers that everybody uses won't even work around cell phones! You can hear your cell-phone call "home" occasionally if you set it anywhere near your PC speakers. It may be that Wall Mart had problems with only PC speakers near transmitter sites. That's a given. They have zero shielding and are designed like large aperture arrays!

The most likely scenario with the Wal-Mart case is their employees started to question working around "high intensity electromagnetic radiation." These are the people who can't live without their cell-phones or microwave ovens, but claim that the "stuff" that comes from those towers interferes with the sex-life of a Tessie Fly and is, therefore, going to mutate their genes so they conceive children with horns.

Wal-Mart lawyers probably said, "Let's not fight that battle!"

Cheers,
Richard B. Johnson
Book: http://www.AbominableFirebug.com/

----- Original Message -----
From: "Bill Harms" <philcobill at verizon.net>

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Wal-Mart announced it is no longer interested in building a supercenter 
at 44th Avenue and Regal Street in Spokane. Saying that nearby 
transmission towers would interfere with store computers necessary for 
operations....