[Elecraft] ERR IO3 more!!

[W2RU - Bud Hippisley]

1.  Unless you have a shielded power line coming to your house, it's unlikely the lightning surge you describe would appear on the telephone line yet go "undetected" by the power lines.

2.  The most probably cause of the damage you describe is that the power line ground / entry point, and the telephone line ground / entry point to your dwelling were not the same.  I believe your modems (and the other PC hardware they were connected to) were destroyed by the _difference_ in the lightning-induced common mode voltages on the power lines and telephone lines at the point where they connected to your PCs.

I, too, have suffered this kind of damage -- damage limited to those devices that are bridged across power and telephone lines.  The solution is to bring both (or all) utilities into the house at the same entry point (and your antennas and control lines, too, of course), and to make sure the grounds of everything are tied together at that point.  You want all your electronics equipment tied together in low-impedance fashion (at lightning frequencies -- i.e., in the 1+ MHz range) so that everything rises and falls together with the surge on the utility lines.  Adding other protection (UPSs, surge suppressors, etc.) may be helpful but most of that stuff will be overwhelmed when the two utilities feeding your PC and modems are not surging in unison.

Bud, W2RU  


On May 1, 2011, at 7:48 AM, R. Kevin Stover wrote:

> At my former QTH...I lost at least 3 modems to nearby lightning
> strikes, one of which took the computer motherboard, all on-board Ram,
> the video card, and one of two hard drives with it. All of that was
> destroyed by the simple phone line connection. Nothing else in the
> house was destroyed so the surge didn't come in on the power connection.
> 
> The lightning strike that did this mayhem was 200 yards away and blew
> up the maple tree it hit. It also induced a large surge in the phone
> lines hanging from the pole next to it.