My coax feeds all go through an entry panel on which are mounted ICE lightning protection devices. These provide a DC ground on the antenna side and no DC path to the rig. My open-wire feedline has a pair of 500K resistors to ground. Finally, I have a relay box which selects the antenna per band and is driven by a KRC2. Those relays default to ground the rig input when the power is off.
On 2/24/2011 10:23 PM, Ron D'Eau Claire wrote: > When my antenna is disconnected (as it always is when I'm not operating) it > is connected to an earth ground. > > Ron AC7AC > > -----Original Message----- > Fred, > > While the K3 has static protective devices that have been mentioned by > others, I prefer to err on the side of caution. The UHF connector has > one problem for antenna/feedline static charge - if the antenna has > built up a static charge, when the feedline is connected to an SO-239 > jack, the center conductor makes contact first, followed by the shield. > So the best solution is a DC path provided within the antenna/feedline > system itself rather than relying on any protection in the K3. > > Type N and BNC connectors do it differently, the shield is connected > prior to the center conductor, thus allowing any charge on the feedline > to be safely discharged through the radio's protective devices. With > UHF connectors, the radio's protective devices may not work because only > the center conductor of the feedline is connected, and there is no > return path to the coax shield until the shell is properly tightened. > > With UHF connectors, any "antenna disconnection" would best be done > using an antenna switch rather than a physical disconnection. The > disconnect will cause no harm, but the re-connection can do damage > without warning. The antenna switch itself is a good place to provide > that DC return path - either an RF Choke (100 uHy) or a high value > resistor (500k to 1 megohm) between the center conductor and ground of > the common connection to the transceiver. When the transceiver is not > in use, switching to a dummy load is a prudent thing to do, so if you > have 5 antennas to switch, a 6 position switch is best with a dummy load > connected to the 6th position. > > Note that this is applicable to any transceiver - I know the question > was asked about the K3 specifically. > > 73, > Don W3FPR > > ______________________________________________________________ > 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 -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ ______________________________________________________________ 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
