[R-390] EMP

[Shoppa, Tim]

Steve asks:

> So, theorectically, what would be involved in "hardening" a
> hamshack?? (understanding that the power grid, etc., would be taken out)

> Not being an engineer and having no background in this area, my
> guess would be some sort of shielding on all sides of the room, roof
> and floor (what would be considered adequate?); thorough grounding
> of the shielding and associated equipment (would the lightning strike
> damage prevention techniques discussed a little while ago be applicable?);
> and filtering of all wiring coming into and out of the room for
> excessive voltage pulses???  Or would even those techniques
> have their own issues?  Just curious.

IMHO: Anything hooked up in any way to an antenna or the power grid
will get fried by EMP. Anything hooked up to a piece of equipment that
is hooked up to an antenna or the power grid will get fried by EMP.

Think that coax switch is gonna stop the pulse
from getting in? Think that AC switch on the power strip is gonna stop
the pulse from getting in? I don't think so.

Any equipment-to-equipment cabling will have large enough voltages
induced across in a major EMP event that connected equipment will be fried.

I think mongo expensive filtering at entrance panels will do good for lesser EMP
events (as well as lightning strikes), but not for worst-case EMP. Copper
ground rings around the ceiling and floor, as in hardened telco facilities, will help with
lesser events too but I would not trust them to stop all EMP effects on 
intraequipment in-room cables.

IMHO the only solution is spare radios and generators
not connected to anything. No dangling cables. Metal cabinets
and cases around more sensitive equipment will help. Cabinets
should be as small as physically possible and panels well bonded.

I'm not going to claim that it's impossible to shield an entire room but
with my much lesser experience with 13.8kv on enclosures, I would
not trust anything unless it had been very thoroughly bonded and this
gets harder and harder with bigger and bigger rooms. Little boxes are
quite easy in comparison.

13.8kv is tiny compared to the megavolts that will be induced by a full
scale EMP strike. But I've seen what I thought were solid well bonded
metal panels open up with lightning storms on every single seam when
the enclosure got hot with 13.8kv. I talk with some abstraction about
EMP events but the 13.8kv hot enclosures I've seen scare me senseless.

And I don't have full confidence that any of this will prevent
damage to all solid state equipment although it will certainly help a lot.

I have some solar panels on the roof which come in handy when storms
take out the power lines, but the copper wiring from the solar panels
to the battery banks will, undoubtedly, be a major entry point for an
EMP pulse.

Tim N3QE