Hi

FYI, seems your email addr here dosn't work, if it's a real one

Dear Amos

i saw your post and hope you wouldn't mind if i asked you a quick
quesiton


Your Icom that was damaged, was unplugged from everything so how did
lightning 'get to it'??

I was kinda distrubed trying to figure it out


V sory to hear of your damage

ml


In article ,
Amos Keag wrote:

Robert11 wrote:

Hello:

The more I read up on this subject, the more confused I get.

SNIPPED

Questions:

a. For either unit, is the arrestor placed between the Balun and the
antenna, or between the Balun and the radio ? Why ?

First, the comment in another response regarding direct strike is mostly
valid. No arrestor will protect from direct strike. [up to 100,000
amperes in less than 1 microsecond, with a 20,000 volt per meter E field.]

Second, for near strike, the arrestor should be installed depending on
arrestor design. For coax based designs installation should be between
balun and radio. For open wire design it should be installed at the wire
to balun interface. Near strike is a non precise technical term. For
near strike in the 10,000 E field zone the arrestor probably won't
provide the protection you seek. For the 1,000 E field zone you should
get some protection.

Why? When the arrestor ignites, fires, actuates there still is a voltage
across the arrestor. This is the net voltage from the plasma in the
spark gap or in the ionized internal gasses. This net voltage transient
has a power density that extends from BC/MF [160 meters] to the HF/VHF
boundary around 30 MHz. It is a broadband pulse. The question is how
much voltage can the radio be exposed to without damage?


b. The Polyphaser unit apparently, when triggered, shunts the charge (only)
to the coax shield. The only path to ground would then be up to the radio,
thru the
chassis, and then to the AC power ground.

Or, I guess, possibly back the other way via the Balun's ground ? Or both ?
I would also image that the Balun's windings would probably blow too quickly
to truly shunt any pulse to its ground ?

There doesn't seem to be any separate ground lug, like the ICE units
have from their pictures.

I'm a real novice with this lightning protection stuff, so I am
probably missing something, particularly with the Polyphaser
shunting-to-the-shield-only approach which
doesn't seem too great regarding how an adequate RF ground is reached for
any
diverted strike/pulse.

What am I missing or not considering with the Polyphaser approach ?
Thoughts on ?

c. Any opinions on the Polyphaser vs. the ICE units for a receiving only
application ?

Much thanks,
Bob


The best solution is to disconnect the antenna and move it away from the
radio when not in use.!!

I'm a retired Aerospace/Electrical engineer who spent years designing
for lightning strikes both direct and near strikes. My station is 100%
conforming to electrical code and lightning mitigation techniques. Last
July, a near strike lightning pulse caused the ground fault interruptors
for the pool, the bathroom and the kitchen to function. The circuit
breakers in the service panel for the basement power distribution
opened, and the power transformer on the utility pole about 1/2 mile
away exploded. I lost my ICOM 756 ProII which was disconnected from the
power lines, notebook computer, USB damage in a second computer on the
in-house LAN, and one telephone. The ICOM 756 Pro II was disconnected
from the antennas, and the lightning surge protectors did not actuate. A
post fault failure analysis indicated that there was a surge in the
utility power neutral to ground. The entire neighborhood of over 50
homes suffered some degree of damage. It is estimated by the power
utility that the strike was 1/2 mile away.

My ICOM 746, my Kenwood TM-G707, and the numerous power supplies
suffered NO damage. Go Figure :-)

CONCLUSION: Lightning finds way to kill electronics no matter how well
the equipment is installed.