------------------------------<snip>---------------------------- > I remember my first (and last) radio kit emitted a barely audible > high-pitched "whine" when turned on. The only other detail I remember ------------------------------<unsnip>----------------------------
Now you're making a connection back to the original article. That high-pitched "whine" was from high frequency magnetic fields causing the internal ferrous parts of the tube to vibrate. This would sometimes be at harmonic frequencies that would cause the external tube or even the mounting surface to vibrate, making the sound audible. Nearly all of what we encountered tubes in as consumers were analog devices. Now put those tubes in a computer, a digital device and start pushing square waves through them instead of nicely curved analog wave forms. Magnetic fields that are basically going from full on to full off repeatedly. Small ferrous parts getting jerked back and forth all over the place. I bet that "hummer" buzzed like a hive of angry bees. Bill Bass Senior Applications Developer United Health Care Greenville, SC This e-mail, including attachments, may include confidential and/or proprietary information, and may be used only by the person or entity to which it is addressed. If the reader of this e-mail is not the intended recipient or his or her authorized agent, the reader is hereby notified that any dissemination, distribution or copying of this e-mail is prohibited. If you have received this e-mail in error, please notify the sender by replying to this message and delete this e-mail immediately. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
