[Elecraft] Automatic lightning protection for radios, .... an off the wall idea

[Jim Brown]

On 1/18/2021 9:09 AM, Bill Frantz wrote:
> While serious lightning protection for structures and other robust 
> things must be done outside the building, I have heard reports of K3S 
> USB chips being fried from currents induced in the USB cable attached to 
> the radio, with the suggestion of disconnecting the cable to protect the 
> chip. I don't see how to do this disconnect outside the building.

Right. That is the kind of failure that proper grounding and bonding are 
able to protect against. It's also the kind of destructive failure that 
the use of MOV surge protectors can CAUSE.

> When I consider a direct strike on my shack's lighting rods, I see 
> massive currents flowing down the thick aluminum cables from the rods to 
> the grounding system. I see these currents inducing currents in any 
> wires in the house, including the USB cable. The lightning rods are the 
> first level of protection, but may not be enough to protect sensitive 
> electronic equipment. Remember, when we work on these radios, we have a 
> grounding wrist strap and a conductive mat on the work surface etc.

That's another thing the proper grounding and bonding protect against. 
But lightning induces current not only on that external wiring, but also 
wiring within the building. IEEE studies show that up to 3kV can be 
induced on internal wiring by a strike!

73, Jim K9YC