Gentlemen, I have a 31 meter tall bottom fed vertical in Florida that is located right on the edge of the water. It gets hit two or three times a year (not always directly). I used to suffer serious damage until I installed the following lightning protection:
1. Whenever I switch the power off to the transceiver, a "linear actuator" automatically grounds the bottom of the vertical via a 5 cm (2") wide ground strap (to a substantial ground). The linear actuator is a surplus from a boat, where it was used as a trim-tab actuator. It has about a 10 cm (4") throw, so it does not cause any stray capacitance when in the retracted position. An alternative could be an old Satellite TV dish actuator. You can often see them cheap at hamfests. 2. At the same time a 20 kV normally open vacuum relay dsiconnects the coax center conductor. 3. At the shack end the coax is rolled into a .7 meter (2') diamter, 6 turn coil. At the entry point, the braid of the coax is grounded to large ground bar and a ground system of four 2 meter ground rods. Another vacuum relay disconnects the center conductor of the coax going into the shack and grounds it (i.e. the PA output gets grounded). 4. On the 240 VAC power side, I have installed three 60,000 A varistor type surge absorbers connected in a delta configuration (i.e. one arrester each from L1 and L2 to ground, and one between L1 and L2.) I have also installed the same on the main AC panel, where the AC service enters the house. That surge arrester group uses the utility ground. While all the above sounds excessive and a big job, it took that much to be able to survive hits without damage or the need to disconnect equipment all the time. Earlier, I have tried gas discharge surge arresters, etc., but nothing really worked 100%. Since I have installed the above system I had no problems. (But I had to replace the grounding strap once, as it partially melted during a big strike.) GL, George, AA7JV _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
