Brett, I did not intend to say that you should disconnect your equipment from the safety gound - only that you may need to supplment it with an RF ground at the place where your equipment connects to the antenna system. In other words, both are necessary, and can work in conjunction with each other.
73, Don W3FPR -----Original Message----- W3FPR continued from K9YC: >Well said - for years now I have been trying to convince folks that there is >a strong need for considering 2 'grounds' at a station. >The first is the Safety Ground which should be a low impedance path to >earth - large conductors, lots of heavy guage wire buried in the earth and >ground rods, and this must also be connected to the utility ground. >Properly implemented it should serve a a lightning protection ground. > >The second is the RF Ground - and the Safety Ground may or may not suffice. >Consider a good Safety Ground with an 8 foot connection from the antenna >connection at the tuner - that combintion will likely produce a high >impedance for RF at 10 meters, thus there will be no RF Ground at that >frequency. In such conditions, the use of quarterwave counterpoises for >each troublesome band is in order. Yes, important distinction & worth mentioning! When not physically close to ground level, that safety ground in the shack can bite you in the bum, such as in Don's example. Few here can establish shack safety or antenna safety grounds that are not going to do something untoward. And antennas usually require roof access, a roof that often has to be directly over your head (top floor flat). This makes RF in shack a big problem. Computer keying, mic switching & voice keyers don't like RF. In such an extreme environment, usually with no option to move anything around, I have yet to try an artificial ground. This despite four feeders plus few control cables running straight into shack from series-fed roof tower as low band vertical - common-mode chokes have always done the trick. They also help keep noises from shack from getting back into the antennas. I could drop all the bonding between major boxes in the shack (rigs, amps, switching gear), but that is my solution for redundant safety ground when operating as total disconnect is also practiced inside during lightning. The bonding also helps a bit with computer keying (often only way to keep from latching key down when transmitting into the roof tower vertical). Few solar cycles of experience from two to 39 floors up here that may help those in more pedestrian situations. The artificial ground is like what I am trying to avoid in the station, so would really be a last resort & one that has yet to be needed. Saying that, I also will not use any end-fed wire or similar antenna that is certain to be problematic - for a temporary set-up where I had to use that sort of antenna then an artificial ground could be the ticket but then certain to hear that computer, telly, etc... unless near field dominates, choke that common-mode stuff & you're likely to prevail. 73, VR2BrettGraham _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.392 / Virus Database: 268.7.0/345 - Release Date: 5/22/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.392 / Virus Database: 268.7.0/345 - Release Date: 5/22/2006 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
