This appears to be a question from January 20, 2010, so it is a little late, but a person never wants to connect the ground rod of the K9AY antenna or any other small or low receiving antenna to the mains ground.
First, it would kill the advantage of having the antenna. If you are going to do that, don't bother installing the antenna. It will hurt the antenna in more than one way. Second, it is not necessary for safety. It is not a large tall structure and is not likely at all to be involved with a direct lightning hit, and even if it were hit the ground at the cable entrance to the house would provide all the required protection. The shack ground and the antenna entrance ground should be bonded to the mains, but the K9AY or any other low noise receiving array must have an isolated ground. The cable leaving the receiving antenna should be buried, should have common mode isolation, and should be grounded at the house entrance to a ground that is bonded to the mains ground. 73 Tom ----- Original Message ----- From: "Robert Mcgraw" <rmcg...@blomand.net> To: "Bill Coleman" <aa...@arrl.net> Cc: <elecraft@mailman.qth.net>; <d...@w3fpr.com> Sent: Sunday, April 18, 2010 10:35 PM Subject: Re: [Elecraft] Grounding negative side of power supply? Yes, do provide a driven ground for the K9AY receiving antenna. This is required for lightning protection. AND be sure to bond this ground to the AC mains ground for the house. Failure to do this will produce a voltage difference or step voltage between the two ground during a nearby lightning strike. The voltage difference can be enough to damage or destroy the radio connected between the antenna and the AC power. AND, bonding of all grounds to a common point is a requirement of the NEC. Remember, lighting has traveled through several thousand feet of air. A balun will offer little to no protection in this regard. Now placing a choke balun or a 1:1 current balun at the feed point will reduce common mode noise on the coax feed line. 73 Bob, K4TAX > > On Jan 20, 2010, at 11:47 PM, Richard S. Lindzen wrote: > >> Dear Don, >> >> This leaves me a bit concerned. I am planning to put up >> a K9AY >> receiving antenna in my backyard and it is supposed to be >> connected >> to a ground rod. I had never seen it suggested that this >> must be >> connected to the utility ground stake. I'm not even sure >> where the >> utility ground stake is. I've never noticed one though I >> will ask my >> electrician. If there is one, it is likely to be pretty >> far from the >> K9AY. > > For the K9AY, your best bet is to make sure the antenna > ground and the > coax ground are completely isolated. I do this by > magnetically coupling > the coax with a 9:1 transformer. Otherwise, common-mode > noise can move > out the shield and be picked up by the antenna. > > Bill Coleman, AA4LR, PP-ASEL Mail: aa...@arrl.net > Web: http://boringhamradiopart.blogspot.com > Quote: "Not within a thousand years will man ever fly!" > -- Wilbur Wright, 1901 > > ______________________________________________________________ > 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: A known bad url was replaced by VIPRE > Please help support this email list: A known bad url was > replaced by VIPRE > ______________________________________________________________ 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: A known bad url was replaced by VIPRE Please help support this email list: A known bad url was replaced by VIPRE ______________________________________________________________ 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
