You are absolutely correct -- having a lightning suppressor installed will not stop a direct hit. ?But a properly installed lightning protection system will -- in most cases. ?I've seen over six sites where the antenna was vaporized, but nothing else was damaged. ?
A roof-mounted antenna is more of a challenge, if you don't have a ground-mounted metal tower or mast supporting it. ?It that case, you need to treat the antenna as a lightning rod and run at least 1/0 AWG wire (8mm diameter) from the antenna mast or mount to multiple 8' long ground rods. ?The ground rods should be spaced apart twice the depth of the ground rod's length. This will provide a lower impedance path to ground than the coax shield. ?Bond the coax shield to the mast, just below the 1/0 wire.
Run the coax to ground level to a GOOD lightning suppressor, properly mounted to a THICK copper bus bar, which is connected to multiple bonded ground rods with #4 AWG copper wire (5mm D.). This can be at the same ground rods used for the metal mast or separate ones.
From the lightning suppressor, run coax?and at least a #6 solid copper wire?to the radio area.?
Bond the lightning ground rods for the mast, lightning suppressors, and house electrical service panel together using at least #6 AWG copper wire (or as required by local electrical building codes). ?Any phone, cable TV, satellite TV, etc. cables must have lightning protection, which is bonded to all the other grounding systems with at least #6 copper wire.
That's a simplified description of the basic principles. ?It's important to understand how properly designed and installed lightning protection is supposed to be done, so you can apply the principles to your situation. ?If you know hams that support local repeaters, ask if you can visit some tower sites and see how it is supposed to be done. ?Most commercial towers take many direct lightning strikes a year with little damage.
Depending on your antennas, a good whole house lightning protection system can run 300-1000+ USD. ?That includes surge suppressor on the main electrical panel, all other utilities, ground rods, copper wire, ground clamps (or exothermic welding of wire to ground rods preferably). ?That's less than the cost of replacing everything every few years.
It's unfortunate that there isn't a good reference for hams on this topic. ?Polyphasor had one, but it is out of print now. ?There are pdf files of it on the Internet. ?Search for "Lightning?Protection &?Grounding?Solutions for?Communication?Sites" ?It is about 4.4MB.
Steve, W3AHL
Steve W3AHL