Problem solved! I tried a little aluminum shielding on the control box (the plastic one that supports their wireless sensors), and that was a waste of time. I gave it a shot while waiting for my delivery of ferrite cores from Mouser. Didn't cost anything and was worth a try.
The security system RFI was cured by inserting, at the vertical's feed point, a choke made from a stack of five ferrite cores (Fair-Rite part number 263180033802) with seven turns of RG-8X passing through the stack. I cranked the KPA500 up to 550 watts and not a sound was heard from that alarm system. Cool. A side benefit to this was that I have a lower SWR at my desired "sweet spots" on 40 - 10 meters. So, placing the string of five ferrite beads on the coax (per a manufacturer's "RFI Kit"), simply wasn't getting the job done. The five mix 31 cores from Fair-Rite (actually from Mouser) did the trick. Thanks for everyone's suggestions! And especially thanks for the good information on K9YC's web pages. 73, Jim / W6JHB On Sunday, Mar 18, 2012, at Sunday, 8:51 AM, Jim Brown wrote: > On 3/18/2012 7:05 AM, Jim Sheldon wrote: >> I trip every GFI outlet in the house. I haven't found enough big snap-on >> ferrites to hit all the romex coming out of the panel, but when I do, I'll >> certainly put 'em on. A really big one that would snap around the incoming >> line at the panel would be nice, but so far I haven't found a source of snap >> on's that I can afford. Not sure either on what material would be best for >> that. > > As was noted in another post, the ones that trip are defective (poor > design). The solution is to replace them with GOOD ones. > > As K2VCO noted, ferrite beads clamped onto a wire are next to USELESS > for HF RFI. Ferrite chokes work by adding a parallel resonance in > series with the wire that they surround, and a single bead or clamp-on > is resonant around 150 MHz. To make it useful at HF we must move the > resonance down to the HF bands by winding multiple turns through it. > > Study http://audiosystemsgroup.com/RFI-Ham.pdf for a detailed > explanation and lots of detailed advice. > > 73, Jim Brown K9YC > ______________________________________________________________ > 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 ______________________________________________________________ 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
