Would this radio survive an EMP attack?

originally posted by: Greathouse

Would the EMP effect be increased if the radio was both plugged in and on? The radio could be plugged in but no power would be reaching the tubes because they event close the circuit until the armed switch is turned on.

With EMP, you get two major effects. One, you get a prompt RF burst that can take out the front ends of receivers and miscellaneous logic gates by inducing high voltages on antennae and long PCB traces. It'll induce high voltages on power lines as well, although they're somewhat protected against it. You will lose your front end caps, possibly cause dV/dt insulation faliure on front end inductors.

The second is a geomagnetic heave. The heave component induces currents in long lines, like power lines. You'll lose transmission lines and power distribution systems to the heave, since it'll walk power transformers up and off their BH curves into the land of saturation where no power transformer should go. At that point, they become short circuits instead of transformers, and burn up.

The heave will also fry up your power transformer, if the design's got one, and it'll pop your filter caps and diodes if not.

So not plugged in, or very heavily protected if so are good ideas.

One last question please. I thought a really strong EMP could damage copper transmission lines?

Is that true or just a urban legend?

It's the heave that does in the long lines. But it's possible to rig them to be ok with it. We just don't, because $$$.

originally posted by: Bedlam

originally posted by: Greathouse

Would the EMP effect be increased if the radio was both plugged in and on? The radio could be plugged in but no power would be reaching the tubes because they event close the circuit until the armed switch is turned on.

With EMP, you get two major effects. One, you get a prompt RF burst that can take out the front ends of receivers and miscellaneous logic gates by inducing high voltages on antennae and long PCB traces. It'll induce high voltages on power lines as well, although they're somewhat protected against it. You will lose your front end caps, possibly cause dV/dt insulation faliure on front end inductors.

The second is a geomagnetic heave. The heave component induces currents in long lines, like power lines. You'll lose transmission lines and power distribution systems to the heave, since it'll walk power transformers up and off their BH curves into the land of saturation where no power transformer should go. At that point, they become short circuits instead of transformers, and burn up.

The heave will also fry up your power transformer, if the design's got one, and it'll pop your filter caps and diodes if not.

So not plugged in, or very heavily protected if so are good ideas.

One last question please. I thought a really strong EMP could damage copper transmission lines?

Is that true or just a urban legend?

It's the heave that does in the long lines. But it's possible to rig them to be ok with it. We just don't, because $$$.

Thank you that issue is finally clear in my head.

But I can't help but find some humor in this thread now. (

So basically you're telling the OP the tubes will be fine. The rest of the radio might be screwed up but his vacuum tubes should be fine. (if it's plugged in)

originally posted by: Greathouse
So basically you're telling the OP the tubes will be fine. The rest of the radio might be screwed up but his vacuum tubes should be fine.

(if it's plugged in)

Mas o menos, si.

What you can do, especially if it's HF, is to rig the front end to take care of the fast component, and NOT use line power.

VHF gets to be a lot more complex.

If you have to survive using line power, you have to build something like the line filter system in a SCIF, only with more teeth.

On the subject of EMP equipment protection, why not go directly to the authoritative source of info, the US army.

MIL specifications, although quite boring to read have all the info you need and are usually available on the web when they are not classified.

See MIL-STD-188/125 MILITARY STANDARD: HIGH-ALTITUDE ELECTROMAGNETIC PULSE (HEMP) PROTECTION FOR GROUND-BASED C4I FACILITIES PERFORMING CRITICAL, TIME-URGENT MISSIONS FOR COMMON LONG-HAUL/TACTICAL COMMUNICATIONS SYSTEMS.

Link

a reply to: AreUKiddingMe

Great radio! They sell those faraday cages on amazon or other places....being that you are so handy you may be able to research and make your own. I think its really tough to gauge what would survive an emp and with my uneducated limited knowledge id wager it is a no. It may be more resistant using vacuum tubes but id imagine there has to be some part or material that could be damaged. I actually keep one tablet and one solar charge in a safe spot. On that little tablet I have 1000s of books. I guess I'll find out someday if the small emp protective sheath works...cause by then I cant get my money back haha.

All a question of the degree of EMP.

As others said, pretty easy to make a protective storage area no matter which radio you used.

a reply to: AreUKiddingMe

No....some of parts will fry

a reply to: Bedlam

Thanks to everyone for the compliments. Thank you for the information and advice, Bedlam, I unplug the radio whenever I'm not listening to it. As far as EMP protection, I think I'm just as confused now and it's probably a matter of speculation until we find out the hard way. This old radio does use a power transformer, and it's a superhet HF receiver, and the front end is very selective and sensitive. That's one thing I like about it. It has a shortwave band, also, and a band called "police" that's no longer in use by police. I could see the front end being destroyed by an EMP, if it was plugged in and on? I'm not sure about the power transformer though. That might go whether or not it's plugged in. There are some old battery operated "farm sets" that are tube radios that use a "B" battery. Now there's companies selling the "B" batteries for this purpose, I think the "B" batteries are pretty much obsolete otherwise. One of those radios might be good to have, because it's battery operated and doesn't rely on the electrical grid.

PeterMcFly, I followed the link and looked at the military specs, and that is way way way more info than I could ever learn about shielding from EMP. More than I ever wanted to know, but I'm glad it's there for someone who can decipher it.

While often reported that microwaves and ovens, etc. can be used as Faraday cages, I'd test this out before depending on it. Easy to check.

Put the ringer on your cell phone on high.

Put the phone in the device.

Try and call it.

Do you hear it? If so, then it won't work as a Faraday cage.

a reply to: Gazrok

Tip: Do NOT have the microwave or oven on. Sorry. I couldn't resist.

A microwave oven's usefulness as a Faraday cage will depend much upon the frequencies you're shielding against.

But... I just did a double test: cell phone in MW using BT earpiece. Called cell from house phone, took about 3 rings before the cell started ringing AND was able to answer and talk with the BT earpiece. So, MW as a cage for cell phones doesn't work so good.

Edit- BT frequency is ~2.4GHz. Cell phone frequency to tower is ~900 MHz.

a reply to: AreUKiddingMe

Valves are resistant to EMP were semi conductors would fry but it would still have to be unpowered.
Some Military aircraft circuit board's including old Top secret (supposedly) circuits are manufactured using micro valve technology instead of semi conductor based transistor/diode technology, they are manufactured using artificial diamond and are supposed to be able to both survive even if powered restart after an emp event that would fry traditional semi conductor circuitry.

So It is more likely this radio would still work than your mobile phone but an unpowered circuit is more likely to survive as the emp can also cause massive power line surges.

originally posted by: AreUKiddingMe
a reply to: bluemooone2

a reply to: bluemooone2

It's a great hobby and the electronics are pretty simple for anyone who is inclined. This pic is the chassis when I first took it out of the cabinet for repair. The tuning mechanism is at the very bottom of the pic, it's called a variable capacitor. Two sets of rows of metal plates that mesh together when you tune the radio but don't touch each other.

*****Beautiful!*****

I am one of those folks that just can't throw out anything electronic until I have exhausted all possibilities of trying to fix it.

Still have my 24 year old washer and dryer. Unfortunately I just replaced the agitator dogs to have the darn agitator coupling go bad. At this point it is likely to nickel and dime me death, but it won't make it to the graveyard before I have stripped it of anything that may be reusable.

Great job!

originally posted by: paradoxious
A microwave oven's usefulness as a Faraday cage will depend much upon the frequencies you're shielding against.

But... I just did a double test: cell phone in MW using BT earpiece. Called cell from house phone, took about 3 rings before the cell started ringing AND was able to answer and talk with the BT earpiece. So, MW as a cage for cell phones doesn't work so good.

Edit- BT frequency is ~2.4GHz. Cell phone frequency to tower is ~900 MHz.

What about an old refrigerator, or wash machine, or dryer?

Might as well check before I have them hauled away.