[PVRCNC] Re: [PVRC] Lightning protection

[Bill Tippett]

At 10:30 AM 7/29/05, you wrote:

>Hi Bill,
>The equipment was not connected to the AC line, antennas or telephone 
>lines.  The 110VAC to the input to Isobars was removed from the wall 
>outlet.  The output coax from the Ten-Tec amp was just laying on the 
>floor, about a 6' RG-8 cable.  I left all of the intra  cabling between 
>the equipment connected.
>
>We had a discussion in the FL area concerning huge surge currents coming 
>in via ground connections thus I had removed all equipment connections to 
>my local 10' copper ground rod.
>
>The Ten-Tec 425 amp input PC board had a big burn mark on the PC board. 
>This input was connected to the FT-990 output via a 4' lenght of RG-58. 
>The FT-990 seems to be OK.
>
>Now in all of this equipment which was just sitting on the desk together 
>the following was damaged.  The W1GEE serial I/F between the radio PC and 
>FT-990, the Astron 35 amp power supply appears to have had a small 
>regulator IC blown, in my HB Idiom press keyer, a 78L05 regulator was 
>blown.  Moreover, all memories in the FT-990 were at their default state.
>
>On the other side of the room my Dell PC was totally disconnected and the 
>modem was blown.  Interesting enough, I had left a telephone and answering 
>machinc connected to the tel. line and they were blown.  I forgot to 
>removed my xyl's PC connection to the tel. line and that modem 
>survived.  The PC was not connected to the AC line.
>
>I am glad that you have been so fortunate !!!!!  This is the second time 
>for this to have happened in a five year period.
>
>My question is now would I really be better off keeping the ground wires 
>on the gear?  All coax cables shields entering the shack are grounded at 
>the point of entry.
>
>Any suggestions or comments are welcome.
>
>73
>Jack, W3TMZ/4 near the Gulf in Central FL.


Hi Jack,

         Wow!...but a couple more questions:

1.  I assume the phone line was not connected to
your radio equipment in any way.  I think that's
correct but just wanted to confirm.

2.  How far away is your tower from your shack?

         If the problem was induction from a
very close strike, the prudent thing would be
to disconnect all potential "antennas" that could
pick up any induction.  I would also disconnect
the equipment from any ground...i.e. no connections
AT ALL.  Apparently even your 6' of RG-8 was enough
of an antenna to pick up what apparently was an
extremely close strike.  I may not be having problems
because my most likely tower to be hit (180' with
nothing on top) is about 300' away.  I have another
~100' high about 150' away but the Yagi's on it
seem to dissipate charge build-up (although
it has been hit at least once to my knowledge).

         If, as I am assuming, your tower is quite
close to your shack, the only solution may be
to completely disconnect all interconnections
that can serve as pickup antennas.  I have often
heard our house wiring "click" with nearby strikes
which I assumed was internal house wiring induction
(since the service entrance has a surge suppressor
at the meter).  We have never had any damage
other than losing an unprotected DirecTV phone
modem (I forgot about that one when installing phone
line surge suppressors!)

         I thought I was being very prudent, but
now you make me wonder about even removing
interconnections!

                         73,  Bill  W4ZV