Farraday cage time for equipment?


Robin WA7CPA
 

Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Jackson Beard
 

It's very easy to accomplish,  providing you can disconnect the antenna. 

We had mesh cages in the military. 

On Fri, Feb 25, 2022, 07:12 Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Aaron K
 


On Fri, Feb 25, 2022 at 7:12 AM Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Paul Butzi (W7PFB)
 

For small items that won’t be used often (backup HT’s for instance) a good solution is to put them in a metal ammo can and then cover the gap between the lid and the container parts with aluminum tape.

you want space between the conductive container and the equipment, so line the ammo can with some sort of nonconductive padding.

Some people feel that enclosing the gear in an anti-static bag will do.  I suspect the conductivity of the plastic material is not high enough.  And again, you need some padding to keep the enclosing bag a small distance away from the protected gear.  But I am by no means an expert.

A metal footlocker would do nicely if you close the gap between lid and body with conductive tape.

You could always wrap the gear in some sort of non-conductive padding and then wrap that with several layers of aluminum foil.  That’s probably not ideal but…

It is probably ALWAYS faraday cage time.  We don’t get much warning with respect to either solar flares or EMP attacks.

-p W7PFB
73, Don’t forget to smile and have fun!

On Feb 25, 2022, at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:

Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Lou Giliberto (KD7HCW)
 

Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Rowland
 

Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Paul Butzi (W7PFB)
 

What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Jackson Beard
 

A Faraday cage does not need to be an absolute enclosure.


On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:
What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Paul Zoba, W7PEZ
 

I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:


A Faraday cage does not need to be an absolute enclosure.

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:
What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Paul Butzi (W7PFB)
 

Yes, a faraday cage need not be an absolute enclosure.

But an aperture wide enough to admit microwaves will admit, well, microwaves and anything with shorter wavelength.

And a wire running from outside the cage thru the wall into the cage will pretty much just be an antenna outside connected to an antenna inside.

-p W7PFB
73, Don’t forget to smile and have fun!

On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:

A Faraday cage does not need to be an absolute enclosure.

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:
What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 







Jackson Beard
 

At USAF critical defense installations we literally used mesh cages. Think about how electrical or radio energy moves in a conductor.

A solid cage is only more effective against a broader frequency range.

On Fri, Feb 25, 2022, 18:56 Paul Zoba <pezoba@...> wrote:
I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:


A Faraday cage does not need to be an absolute enclosure.

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:
What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


Jackson Beard
 

Regarding a microwave - it's a Faraday cage on 5 sides and a Faraday shield on the magnetron side.


On Fri, Feb 25, 2022, 19:20 Jackson Beard via groups.io <macleanofduart=gmail.com@groups.io> wrote:
At USAF critical defense installations we literally used mesh cages. Think about how electrical or radio energy moves in a conductor.

A solid cage is only more effective against a broader frequency range.

On Fri, Feb 25, 2022, 18:56 Paul Zoba <pezoba@...> wrote:
I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:


A Faraday cage does not need to be an absolute enclosure.

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:
What about the gap thru which the magnetron injects microwave radiation into the cavity? 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:


Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.


Thanks,

Rowland



On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:
Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)


Sent with ProtonMail Secure Email.

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:
Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 


 

I find it interesting in this old video that the radio, gas and grid equipment managed to survive. Perhaps some real testing is needed on the effects of EMP on de-energized equipment would be of use.

 

Ken W7ECK

 

From: snovarc@snovarc.groups.io [mailto:snovarc@snovarc.groups.io] On Behalf Of Jackson Beard
Sent: Friday, February 25, 2022 7:33 PM
To: snovarc@snovarc.groups.io
Subject: Re: [SnoVARC] Farraday cage time for equipment?

 

Regarding a microwave - it's a Faraday cage on 5 sides and a Faraday shield on the magnetron side.

 

On Fri, Feb 25, 2022, 19:20 Jackson Beard via groups.io <macleanofduart=gmail.com@groups.io> wrote:

At USAF critical defense installations we literally used mesh cages. Think about how electrical or radio energy moves in a conductor.

 

A solid cage is only more effective against a broader frequency range.

 

On Fri, Feb 25, 2022, 18:56 Paul Zoba <pezoba@...> wrote:

I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:



A Faraday cage does not need to be an absolute enclosure.

 

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:

What about the gap thru which the magnetron injects microwave radiation into the cavity? 

 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p



On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:



Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.

 

 

Thanks,

 

Rowland

 

 

 

On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:

Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

 

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

 

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)

 

 

Sent with ProtonMail Secure Email.

 

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:

Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 

 


 

Ugh, help if I added the link.

 

https://www.youtube.com/watch?v=thPfjOt5WEo

 

Ken

 

 

 

From: snovarc@snovarc.groups.io [mailto:snovarc@snovarc.groups.io] On Behalf Of Ken Kosters via groups.io
Sent: Saturday, February 26, 2022 7:51 PM
To: snovarc@snovarc.groups.io
Subject: Re: [SnoVARC] Farraday cage time for equipment?

 

I find it interesting in this old video that the radio, gas and grid equipment managed to survive. Perhaps some real testing is needed on the effects of EMP on de-energized equipment would be of use.

 

Ken W7ECK

 

From: snovarc@snovarc.groups.io [mailto:snovarc@snovarc.groups.io] On Behalf Of Jackson Beard
Sent: Friday, February 25, 2022 7:33 PM
To: snovarc@snovarc.groups.io
Subject: Re: [SnoVARC] Farraday cage time for equipment?

 

Regarding a microwave - it's a Faraday cage on 5 sides and a Faraday shield on the magnetron side.

 

On Fri, Feb 25, 2022, 19:20 Jackson Beard via groups.io <macleanofduart=gmail.com@groups.io> wrote:

At USAF critical defense installations we literally used mesh cages. Think about how electrical or radio energy moves in a conductor.

 

A solid cage is only more effective against a broader frequency range.

 

On Fri, Feb 25, 2022, 18:56 Paul Zoba <pezoba@...> wrote:

I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:



A Faraday cage does not need to be an absolute enclosure.

 

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:

What about the gap thru which the magnetron injects microwave radiation into the cavity? 

 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

 

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:



Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.

 

 

Thanks,

 

Rowland

 

 

 

On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:

Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

 

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

 

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)

 

 

Sent with ProtonMail Secure Email.

 

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:

Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically? 

 


Rowland
 

This is the same film they showed us when I was training to work on Minuteman Missiles in 1970.

I find it interesting they were allowed to enter the blast area within 24 hours.  Would be interesting how many workers suffered from radiation poisoning later on in life.


Thanks,

Rowland



On Sat, Feb 26, 2022 at 7:54 PM Ken Kosters <kenkosters@...> wrote:

Ugh, help if I added the link.

 

https://www.youtube.com/watch?v=thPfjOt5WEo

 

Ken

 

 

 

From: snovarc@snovarc.groups.io [mailto:snovarc@snovarc.groups.io] On Behalf Of Ken Kosters via groups.io
Sent: Saturday, February 26, 2022 7:51 PM
To: snovarc@snovarc.groups.io
Subject: Re: [SnoVARC] Farraday cage time for equipment?

 

I find it interesting in this old video that the radio, gas and grid equipment managed to survive. Perhaps some real testing is needed on the effects of EMP on de-energized equipment would be of use.

 

Ken W7ECK

 

From: snovarc@snovarc.groups.io [mailto:snovarc@snovarc.groups.io] On Behalf Of Jackson Beard
Sent: Friday, February 25, 2022 7:33 PM
To: snovarc@snovarc.groups.io
Subject: Re: [SnoVARC] Farraday cage time for equipment?

 

Regarding a microwave - it's a Faraday cage on 5 sides and a Faraday shield on the magnetron side.

 

On Fri, Feb 25, 2022, 19:20 Jackson Beard via groups.io <macleanofduart=gmail.com@groups.io> wrote:

At USAF critical defense installations we literally used mesh cages. Think about how electrical or radio energy moves in a conductor.

 

A solid cage is only more effective against a broader frequency range.

 

On Fri, Feb 25, 2022, 18:56 Paul Zoba <pezoba@...> wrote:

I’m thinking Yaesu 857 in an ammo box and put that in a gun safe. That should work as long as I can open the safe in the event of an EMP.


On Feb 25, 2022, at 6:49 PM, Jackson Beard <macleanofduart@...> wrote:



A Faraday cage does not need to be an absolute enclosure.

 

On Fri, Feb 25, 2022, 18:38 Paul Butzi (W7PFB) via groups.io <w7pfb=butzi.net@groups.io> wrote:

What about the gap thru which the magnetron injects microwave radiation into the cavity? 

 

Either the magnetron is outside the shielded cage and there’s a window it injects thru, or the magnetron is inside the cage and there’s a power feed thru the wall of the cage. Either one defeats the cage in the event of an EMP. 

-p

 

On Feb 25, 2022, at 6:05 PM, Rowland <rowland.brasch@...> wrote:



Read an article several years ago about using a non working microwave as it is completely shielded so microwaves cannot leak out during use. So the RF cage will shield equipment inside from bad things on the outside.

 

 

Thanks,

 

Rowland

 

 

 

On Fri, Feb 25, 2022 at 1:20 PM Lou Giliberto (KD7HCW) via groups.io <louis.giliberto=protonmail.com@groups.io> wrote:

Here's the nerd answer:  https://physics.stackexchange.com/questions/230728/would-a-faraday-cage-protect-something-from-an-emp

Having used them for telcoms stuff, you really do need to make sure they are "completely sealed".  Any kind of wire running out from them (e.g., power) will cause signal and such to leak in.  

 

They also make "faraday bags" which are what they sound like - a bag you put an object into and it provides some measure of protection.  We used that and a metal garbage can with a ground strap when we wanted to test loss of signal stuff for telecoms.  Cell phone signals are designed to be very aggressive so that our phones work.  If the EMP burst is purposeful, it, too, will be aggressive. There are also "faraday tents" but they often leak like a sieve.

 

Step one is the EMP burst on the equipment.  Step two will be the EMP burst effects on your power source (e.g., the grid, generators, batteries) and anything along the antenna path that is susceptible (e.g., rotor, loop amplifier, etc.).

+1 for tube amps which are more resistant to the effects.  Sometimes the old ways are the best ways. I should build a spark gap transmitter ;-)

 

 

Sent with ProtonMail Secure Email.

 

------- Original Message -------
On Friday, February 25th, 2022 at 7:12 AM, Robin WA7CPA <wa7cpa@...> wrote:

Someone on 100 Watts and a Wire suggested it may be Farraday cage time. Only asking for suggestions on creating them.  Not trying to start a geopolitical discussion. Seems easier for the handhelds.  My biggest concern is HF equipment. Pointless to try? Metal roof overhead. Basement windows could be covered with what effective material? What about the concrete walls? Anyone delved into this theoretically?