Jim, In an ideal world, the tuner is only an impedance transformation device - but the name of this RF Ground game is the elimination of common mode current from the transmission line and equipment in the shack so that all devices, including the tuner can work as expected with no extra RF floating around.
The RF ground needs to be associated with the antenna system, thus connect to the tuner (or whatever is to be connected to the antenna system). The transceiver does not need an RF Ground. Most modern transceivers are designed to drive a 50 ohm coaxial load. Plus, the transceiver itself will not put any common mode current on the coaxial line - all its energy is inside the coax as a differential output between the coax center conductor and the inside of the shield - there will be no RF energy on the transceiver enclosure or the coax shield that is being generated by the transceiver. So the bottom line is to keep the common mode currents coming in from the antenna system from being coupled back onto the coax shield between the tuner and transceiver. The real proper place for the RF ground is at the antenna, so no common mode energy is ever coupled back to the shack, but this is not a perfect world, and in many cases, the RF ground must be placed at the shack end. If there is a tuner, the RF ground should be placed at the tuner output - EXCEPT, if chokes or baluns are placed between the tuner and the antenna, then the RF ground should be placed at the choke or balun. In other words, looking from the antenna toward the shack, place the RF Ground prior to any device that attempts to eliminate common mode current from the remaining coaxial cables and equipment chassis. There must be a path for that common mode current to flow, and the RF Ground is a proper place for it to flow - it will find a path if one is not provided, but the one found may not be desirable. 73, Don W3FPR > -----Original Message----- > > Don, > > Seems we are in basic agreement. I agree that the equipment termination > point of the ground wire can be a subtle thing. My preference > would be at > the actual point of generating the RF, i.e. the transceiver > usually. Here I > go again, but my way of thinking is an antenna tuner is only an impedence > matching device and has no direct relation to the length of ground wires. > > Jim, AB0UK > -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.17.8/648 - Release Date: 1/23/2007 11:04 AM _______________________________________________ Elecraft mailing list Post to: [email protected] 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
