John, Put a resistor across each feedline is my advice. A value from 22k (I like 3 watts for legal limit rating) to 100k will discharge the static. A DC path across the feedline is a very good protection against antenna static damage to your rig - the path to ground is not as essential as across the feedline, but a path to ground does add benefit as well.
You can add resistors at the feedpoint of your antennas - that gives an added benefit of being able to check for breaks in the feedline, just measure the resistance across the feedline. That does not work for loops since the closed loop should indicate a resistance that is quite low itself. If you care to open the Alpha Delta switch, that is a great place to install them - if you have no other choice, put the resistors in a PL-259 body, one lead to the center conductor and solder the other lead to the shell - then use a Tee adapter to connect the resistor across the feedline. The Gas discharge tubes are effective against large charges - the ones I have will squelch a voltage in excess of 600 volts, but below that level, they will do nothing. That 600 volt surge is enough to take out the diodes in the K2 KPA100. The K3 has more protection. but still should not be trusted when it comes to static charges. The simple resistor across each feedline will bleed off static and help substantially. An alternative to the resistor is a choke (of adequate current capacity for the power of your station). In a 50 ohm system, 100 uHy or greater will be good down to 160 meters. 73, Don W3FPR On 9/8/2012 8:25 PM, zen...@netspace.net.au wrote: > Hello Group, > > I've just re-hung my 80m horizontal loop. With so much wire in the > air, I'm reviewing my static charge risks and how to reduce them to > protect my K3. I'm in the mountains - things get bumpy and charged > up here. I once lost the wattmeter diodes in my K2/100 to a static > event, so I'm looking for prevention. Any advice will be gratefully > received. > > Here's my new setup: > > 80m loop fed with open wire line to a DX Engineering 1:1 balun outside > the shack. A 5 foot length of RG213 brings the signal from the > balun, through the shack wall to an AlphaDelta antenna switch. The > outer shield of the RG213 is connected to the station ground, at the > balun, outside the shack. The AlphaDelta switch is connected also to > the same station ground. It grounds the centre conductor of all > antenna lines when in the "common" position - and I leave it this > way whenever I'm not operating. My understanding is that any antenna > lines are protected by a gas discharge capsule in this switch, which > acts as a "fuse" in the event of significant static discharge on an > ungrounded line? > > "Station ground" here means 2 copper pipes buried in earth outside the > shack and connected by about 6 feet of cable. One of the pipes is in > very damp earth most of the year, the other is sheltered and is in dry > soil. > > Is this setup sufficient to manage static discharge risk from my > antenna, or are there other precautions I should be taking? I've > read about ICE static discharge devices and high value resistors > from both sides of the ladder line to ground. Just looking to > minimise risk without going overboard. > > ______________________________________________________________ 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
