The idea shunt feeding the tower provides "lightning protection" is more
hype than fact.
I have owned several insulated series-fed and shunt fed verticals. The worse
lightning damage (by far) has been while using shunt fed towers. I lost a
T4XC, R4C, large antenna switching relays, vacuum tuning cap on the shunt
wire, and several other components including coaxial feedlines from direct
hits on VERY well grounded shunt-fed towers.
My 200ft and 318 ft insulated towers have taken several hits a year over the
past 4 years with no damage at all (even to the matching networks and
relays) and everything remains connected all the time. Only a single RCS-8V
isolates the antennas from the feed to the house.
I'm not saying one is more immune than another, but if you have simple arc
gaps on a series fed tower it certainly is much better than not having arc
gaps on a shunt wire. A simple shunt inductor will stop all the momentary
gap-flashes from nearby storms.
I learned my lesson the hard way. I don't count "improved lightning
protection" as a reason in making the selection.
73 Tom
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