Hi Jim, and Readers,
I read the piece about using a CONEX as a Faraday cage, I made some RF measurements using a 2-meter handheld, and a small portable Sangean ATS-909 receiver quite a while back with that very subject in mind.
I have an S-250 RATT Rig shelter also. I don’t think you can really beat the S-250 shelter, with any other readily available equipment. But in a pinch even the CONEX will work relatively well for EMI, EMP, and TEMPEST. The reduction of signals even with the wooden floor is enough to help even with no EMI gasketing on the doors,. It is much better than a metal building like a shop or garage. Now, there are available metal equipment shipping containers available at most military surplus houses around the country many with EMI gasketing installed. They are also often available at a lot of Ham swaps for reasonable prices. The main thing is to check the gasketing, If they just have rubber gaskets, they can be replace with conductive gaskets, Just searching “EMI Gaskets” on line will bring up lots of resources.
I have elected to make absolutely sure that when I have even the slightest doubt to use large ammo cans, or electronics equipment shipping containers to place my specialized electronics into. Then I place them in my CONEX or my G.O.O.D. trailer. In my shop, I keep handhelds, including light test equipment in shipping containers.
Even in the S-250 shelter, It is important to secure the connector caps for the RF entrance and power entrance connectors, being sure to also ground the unit with the usually-supplied grounding strap and ground rod.
If you want EMP and CME insurance then take all of the precautions possible to protect what important electronics you have.
I have elected to not only protect quite a bit of my ham gear including several QRP (low power home built radios), but also GMRS, CBs, and test equipment.
I have also placed the business ends of some sound projection equipment in containers too. The reason for this is that I remember in the novel One Second After, they wished they had some way to make public addresses easier.
It is important too that generators, and solar equipment be protected. I know most solar cells are diode protected, but what I don’t know is what the peak inverse voltage is or the clamping voltage is on those diodes. Meaning how much protection will that actually provide, not knowing the actual estimated energy of a threat, my personal choice is to keep my expensive panels secured until well after an event so I don’t have to be concerned weather they will take the punch-thru or not of some unknown current hitting them.
I mentioned CBs I got a good deal several years ago with the manager of the Radio Shack, he let me have for five dollars each all of the returned CB sets, I got about 25 units, out of which I was able to repair more than half. I set them all up with Anderson Power Poles
I am not yet fully prepared, and I don’t think anyone can think of everything. I do have some old computers that are on my list of needing to be checked out and loaded with some ham radio communications programs, then secured in equipment containers too. that includes the whole computer, keyboards, mouse’ mice’s little rats, what ever you know where I’m headed, the whole thing.
I might mention the Earth has been hit just in the past two weeks with two moderate CMEs, And I get a lot of lightning storms around here this time of year, Now if I leave home for any length of time, I have made it a habit of shutting down and unplugging any equipment I consider important enough to protect. including disconnecting antenna systems.
Something to keep in mind even if your antenna gets hit by lightning and it is disconnected from your equipment. The coaxial cable can get arcing punch through for quite a length down the coax from the antenna, and again at the terminating end. Therefore prepared replacement coaxial cable should be considered as part of your preparations. I once had to repair part of a very large antenna system and by the time we were done fixing the system it cost many thousands of dollars before it was made right.
So have some type of test equipment to check out your antenna array before reconnecting it to your critical radio equipment. Then when you bring up your transmitter, bring the power up incrementally ,continuously keeping an eye on the VSWR (SWR) on your antenna. Blessings – Dave in Oregon