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Reg Edwards wrote:
Cec, its obvious even to a citizens bander that when the common-mode current and volts encounters the choke, or anything else, it is reflected. There's no need to risk your neck to detect it. Judging from some of the assertions on the subject, some people consider common-mode current to be a series circuit problem, not a distributed network problem. You won't prove anything anyway. Your particular antenna might not suffer from noticeable common-mode effects. And you can't deliberately inject a test signal at any place because it would upset circuit conditions. I'm running a G5RV right now. All I have to do to gin-up common-mode currents on at least one of the eight HF bands is to remove the choke at the coax to ladder-line junction. Furthermore, the choke does NOT do what the old-wives say it does, ie., stop radiation from the line and prevent noise pick-up. It might even make matters worse. The choke merely shifts the volts and amps standing waves to other places along the line. I use a choke to reduce common-mode problems in the shack and it does that apparently by causing reflection of common-mode waves back toward the antenna which, as you say, wouldn't decrease feedline radiation between the choke and the antenna. Have I upset the apple cart again? Where does the common-mode power go? :-) If differential reflected power can be almost 100% delivered to the antenna by matching, how about common-mode power? What happens to the common-mode reflected power when it gets back to the antenna? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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