MFJ window feed through / lightning
I like the idea of the window feed through. In case of a lightning storm,
one could easily disconnect his antennas from the INSIDE. My question is should one ground the feed-through plate at the window to a ground rod just below the window? First thought - Maybe this would help protect the house. Second though - Maybe it would be better to let the coax float with the tower, to avoid burning out the coax. Third thought - With ground rods at both the tower and the entrance to the house, could this create a noise inducing ground loop? Is there any standard practice about this? -- Bob D. ND9B |
MFJ window feed through / lightning
On Thu, 10 May 2007 23:35:41 -0400, "Bob D."
wrote: I like the idea of the window feed through. In case of a lightning storm, one could easily disconnect his antennas from the INSIDE. My question is should one ground the feed-through plate at the window to a ground rod just below the window? Hi Bob, Only if you want the lightning to go there. First thought - Maybe this would help protect the house. Too many variables unmentioned to guarantee that. Second though - Maybe it would be better to let the coax float with the tower, to avoid burning out the coax. Think of it as a fuse. Do you want it to blow open, or continue feeding a bajillion amps into the ground nearby? (Again, neither of these is guaranteed to occur - too much left unsaid.) This could elevate the local ground potential and if you take too long a stride you could feel half that potential between your legs (does that motivate you?). This is implicit to the next thought: Third thought - With ground rods at both the tower and the entrance to the house, could this create a noise inducing ground loop? Connect the two (and beyond) per standard practices. Is there any standard practice about this? Consult your local library for the code. Such things vary from place to place, but there are commonalities - no doubt many of them will be discussed here shortly. 73's Richard Clark, KB7QHC |
MFJ window feed through / lightning
Bob - An antenna expert (when I lived in central Florida) told me that
floating antennas will attract lightning. So, I always grounded my antennas with an inside switch, and had a 60ft ground rod (washed-in water pipe) directly under the center of my 70' tower base. Unlike many of my ham friends, I never had any lightning damage to my rigs during 17 years of living in the lightning capital. The mast had a number of burns on it when I took it down to move north. I am sure it had more hits than the three I was aware of. The other thing I did was loop the coax down to ground level, and then back up (about 3') and through my window to the grounding switch in the shack (bedroom). The theory there is that lightning doesn't like to reverse direction and will usually jump from the shield to the ground rather than loop back up and come into the house. The open feed line is an invitation for the lightning to find its own way to ground - through your home. I ground my feed lines with an outside switch these days, and so far still have no hits on my radios. However, my antenna switch control box took enough of a jolt from a close hit to burn out one diode. Andy K4YKZ |
MFJ window feed through / lightning
On Thu, 10 May 2007 23:35:41 -0400, "Bob D."
wrote: I like the idea of the window feed through. In case of a lightning storm, one could easily disconnect his antennas from the INSIDE. My question is should one ground the feed-through plate at the window to a ground rod just below the window? I recently installed the MFJ feedthrough, and when bad weather approaches, I disconnect the two dipoles and a j-pole from the OUTSIDE. I hang the feedlines from a small tree outside the window. If lightning hits, I figure it will find its way down the tree. It hadn't occurred to me to disconnect from the inside, and bring the lightning to my window sill. Yikes. bob k5qwg First thought - Maybe this would help protect the house. Second though - Maybe it would be better to let the coax float with the tower, to avoid burning out the coax. Third thought - With ground rods at both the tower and the entrance to the house, could this create a noise inducing ground loop? Is there any standard practice about this? |
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