Gentlemen, I'd appreciate a link to any manufacturer's or engineering data you have, since I have never seen a ferrite or powdered iron core that was permanently affected by a magnet, nor have I ever encountered any manufacturer's warnings about magnets around modern electronics in the equipment I've worked on over the years.
My hardware experience includes repairing aircraft navigation and radio equipment, broadcast transmitters, mobile radio equipment from HF through UHF and repairing and certifying all sorts of communications gear from MF/HF radios to satellite systems, radars, GPS and other navigational equipment on ships of all sizes from fishing vessels to some of the largest deep water vessels afloat. Much of this gear protects lives, and I've always been careful to do everything *by the book* per the manufacturer's instructions and the regulations. It is true that magnets can affect cores by detuning circuits to some extent *while the magnet is present*. Indeed, some systems use a permanent magnet brought near a toroid, or a separate winding through which a d-c current is passed to create a magnetic field, to 'tune' the circuit by adjusting the inductance slightly. Those systems for adjusting the inductance work because the toroid is not permanently affected by the magnetic field. Several years ago a number of Elecraft K2 owners noted the speaker magnet in the top cover affected some alignments. The solution was to be sure the cover was in place first so the field from the powerful speaker magnet was in position just as it would be in normal operation. There are no problems caused by the presence of the magnetic unless it is moved. The only thing I can suggest about the guy with the 2-meter rig that was permanently "detuned" by putting mag-mount antenna on the case is that it magnetized the case itself and the permanent magnetic field resulting from the case affected some nearby toriods. Demagnetizing the case should fix the problem. When I worked in land mobile in the 1980's, people often did exactly that to set up a temporary "demo" installation of 700 or 900 MHz radios without any deleterious effects on their performance. I used to warn against that, not because of the magnet, but because of the very close proximity of the operator to 35 watts of 700 or 900 MHz energy from that antenna when transmitting. I'd suggest Hams avoid doing that for the same reason unless they're keeping the transmit power very low, even on bands as low as 144 or 50 MHz. Ron AC7AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
