On Mon, Apr 11, 2011 at 7:11 PM, Wayne Conrad wrote:
> I want to start out with an loop antenna in the attic, etc.... Wayne, you've already gotten some pretty good advice on this subject. May I add my two cents' worth here? First, you did not make it clear at all if your attic antenna is a 'must' due to CC&Rs or simply your "choice". Wayne, if you have any choice in the matter, put the antenna outside. I have no choice due to CC&Rs so my antenna has been in my attic for the past nine years since we moved into this townhouse. Second, lightning,'close strikes', and static build-up can wipe out your investment in hardware just as easily in the attic as can happen outside. I happen to know this because a Hallicrafters SX-146 practically blew up in my face several years ago. Take the necessary precautions, please! Third, how successful your attic installation will be largely depends upon the particulars of YOUR situation. Some issues can be mitigated; some cannot. Assess your attic environment and if the list of "negatives" outweighs the "positives" then you might want to start investigating some sort of outside 'stealth' setup. In my case, I found my attic to be quite RF friendly. There is no metalized insulation up there, the vents are all PVC, all wiring is below the attic floor, there is no HVAC at all, tthe shingles are asphalt, the ice dam is non-metallic, the gutter runs are extremely short (due to the architecture) and the downspouts are 90 degrees off from my antenna plane and much lower. There were two runs of "slinky-like" 4" bathroom vent hose. I went up and chopped them up into small segments and then put them back together again with duct tape. These are a few things you might want to check out in your attic. Fourth, I run only QRP with my attic antenna. Technically, I can meet the MPE Uncontrolled limits at 100 watts but I prefer not to run higher power. Above a nominal 30 watts I turned on my neighbor's carbon monoxide detector, put my CW signals into her telephone, and turned my own DVD player on and off, on and off. The CO problem was "unfixable" and probably due to the unit's design. The phone problem was solved with the addition of a filter from KY Filters. The DVD problem was solved with a single Mix 43 toroid on the DVD player's line cord. For your information, the antenna I chose to install in my attic is a homebrewed 62' doublet bent a couple times to fix the space available. I avoided doubling it back on itself. The center insulator is the Delta-C surge supressor from Alpha-Delta. I fed it with 14 feet of 450 ohm ladder line directly to an SGC-237 autocoupler on a shelf near the ceiling in a linen closet right below the feedpoint. This keeps the rather expensive autocoupler out of the winter's cold and the summer's heat in the attic. The run from the autocoupler to my station is about 25 feet of RG8X. I have a copper cold water pipe behind my operating desk and I confirmed that it is tied into the electrical panel as per code here in NY. The ground is *not required* in the sense that the doublet is already balanced but it's good practice and I use it. I'm working "the world" on 5 watts, frequently much less, and having all the fun I can handle. I can load up 160 through 6 meters with the doublet. My SWRs are all below 1.4:1 except for 40 meters where I am 1.8. I may need to shorten/lengthen the ladder line somewhat. I guess the message is simply this - evaluate your environment, consider the options, and then go for it. Electromagnetic particles can't read textbooks so they don't often realize that they are not supposed to propagate themselves to the far corners of the world from a measly attic antenna hi! Good luck with your loop! It may surprise you! 73, Stan WB2LQF KX1 #2411 K1#2994 K2# 6980 K3#5244 K9 #1 (Cocoa the Chihuahua) Everything is QRP, even the dog. You seem set on a loop. They work and they work well. ______________________________________________________________ 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
