On Wed, 2011-03-23 at 19:35 -0700, Jim Brown wrote: > On 3/23/2011 1:30 PM, John Lemay wrote: > > Yes, I can "home in" on the noise with great certainty ! > > That indicates that the noise is being radiated by the P3 or something > attached to it, and picked up on your antenna (and not picked up on K3 > wiring).
I can see the noise on mine if I hook a clip lead to the ANT3 (144 MHz) connector and place it close to the display. But I doubt you could hear that on an external antenna. The opening in the front panel is much smaller than 1/2 wavelength on 2 meters, so the far field should be greatly attenuated and the near field falls off rapidly with distance. > The comments by others that ferrites on the power cable killed the noise > suggest that that cable is doing the radiating. Now, I wouldn't rule out > the coax as a radiator if someone has choked the power cable and still > heard noise -- with RFI, always assume that there could be more than one > coupling mechanism. The shells of the coax and the RS-232 connectors are grounded directly to the chassis. Sounds like it must be the power cable. Alan N1AL > Again, let me emphasize that a ferrite core is a low Q parallel resonant > circuit. Most single #31 or #43 cores are, by virtue of their size and > shape, cause a single turn to resonate close to 2M, while more turns > move the resonance down to lower frequencies. This a problem on 2M is > better solved with multiple cores rather than multiple turns, whereas > problems on 6M are better solved with two turns and on the HF bands with > more turns. > > 73, Jim K9YC > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
