How do you make a radio jammer

If you can't laugh, you're dead.

Years ago a college buddy took out at nasty neighbors TV with a magnetron from a micro wave oven. He pointed it at the room his TV was in and waited until he was out and turned it on.
A day later the TV was out on the curb with the trash.

Either it actually worked or it was an incredible coincidence!

inverse square law says to go with the coincidence theory...... microwave ovens use a wavelength of 10cm. assuming 10^5 V/m at 10 cm from the antenna, by the time you get 1 meter away, the E-field, is now 10^4 V/m, at 2 meters, that's 10^2 V/m, at 4 meters that's 1V/m, at 8m that's 10mV/m, and at 16m away from the source that's only .1mV/m. to couple enough energy to damage even an RF input FET, the magnetron would have to be within 3 or 4 meters (9-12 ft) of the tv.

When I was in college one guy also played his stereo so that everyone else HAD to listen to his crap. I took my dad's Earth Leakage (IL) tester, plugged it into a wall socket and turned the dial till the EL tripped out. I then left it in the plug, locked my room and went out for the afternoon. We had no more problems thereafter

Depends on how directional it is unclejed, the inverse square law only works for an ideal isotropic antenna. I'm certain a microwaves magnetron is no where even close to isotropic.

Think i'll chime in also, maybe put the thread back on track .

I worked for Primeco (now Verizon) as a switch technician in San Antonio. We had a cell site that would just suddenly drop out, drop all calls but the T1 was still up and no bit errors. Loopback the CSU run diags, etc and everything comes back clean. The next day another cell site would drop... same two back and forth. Our RF guys would drive the van trying to figure out who was jamming that site. Come to find out, the EOD (explosive ordinance disposal) group would share the bomb robot between Randolf AFB and Kelly AFB (about 30 miles apart). Robot was on our frequency... that took awhile to troubleshoot.

The fastest one was when a University of Texas senior kept taking down one of the cells from his final project. That's pretty easy to track when you stay in your garage. His objections about needing to finish his project fell on deaf ears. When you threaten FCC fines that shuts them down very quickly.

As I recall the bad neighbors TV room was right across a walkway from my buddies bedroom. So there was probably about 10 -12 feet between the wall of his room to the TV.
A magnetron from a 1500 microwave oven should have some power at that distance.
I may be wrong but dont the actual microwaves just emanate from that small hole at the one end? So wouldn't the energy beam be somewhat more directional that way?

I dont play with microwave oven magnetron's. They are one of the few electrical devices I am still shy about.

As far as I know microwave energy tends to scramble electrical devices rather well.
I have seen several science shows that had people using unshielded microwave oven magnetron's. All sorts of odd things would happen to computers, monitors, radios, TV's, cell phones and many other electrical devices when the magnetron's were running. Some things would get heavy static and others just quit.

The bad neighbor was one of those people that take every chance they can to push their own rules on every one they can. He would have other tenants vehicles towed for not parking the way he thought they should. If any one made any noise he could hear in the complex hallways or yards he would get the cops over.
He often swore and yelled at children in the hallways for being noisy or running. He was just a mean and bad person.
As I recall the landlords would not kick him out because he had legal degree and often would just take people to court to waste their time and money. It didn't cost him anything to go to court even over the smallest things so it was a great way to get what ever he wanted.

if it was inside a building, it could have been picked up by the wiring and coupled into the TV by the rather large capacitances of the bridge rectifier. there might be enough energy there to cause some "soft" failures, such as degrading the transistor junctions in any microprocessors, and other chips in the TV, maybe even enough to take out the micro, since it's running off the standby supply, and any soft failures there may turn into hard failures after a few minutes to an hour of operating in a degraded condition, or a lockup condition (which is thermal disaster for small low voltage micros). most oven magnetrons by themselves have an isotropic antenna sticking out. if they're still mounted in their wave guide assembly, there's very little loss until the waves exit to free space, after that the inverse square law takes over. same with directional antennas, all of the gain is in the directional assembly. once the wave get's into free space it spreads out in the same manner as any other wave. in the near field of the antenna, the waves that would have been radiated in all directions are reflected in phase with the direct wave. the antenna has gain in this direction, and all of the direct and reflected energy reinforce each other, so for instance instead of a 100kV/meter measurement 1 wavelength from the antenna, it's now 400kV or 800kV, but once in free space, it's still going to diminish according to the inverse square of the distance, just it's travelling generally in one direction rather than all directions. it's still spreading out. even a laser does the same thing. this is why directional antennas and even lasers are specified according to their beamwidth in degrees or radians a 0.1degree beamwidth of a laser still means that if you measure the lumens per square centimeter of a laser at say, one meter, when you measure again at 2 meters, it will be one quarter what it was at 1 meter and 1/9th at 3 meters. all of the energy of the beam is still there, just spread out more. with a gas laser for instance, the beam width is roughly determined by the ratio of the mirror diameter and the length of the "cavity". even collimation of the beam has it's limits. you will often see fresnel rings on a microwve antenna. the purpose is to collimate the beam. there will still be spreading of the beam, since the beam still contains off-axis components

good. thanks for ur ideas

SPDCHK said:

When I was in college one guy also played his stereo so that everyone else HAD to listen to his crap. I took my dad's Earth Leakage (IL) tester, plugged it into a wall socket and turned the dial till the EL tripped out. I then left it in the plug, locked my room and went out for the afternoon. We had no more problems thereafter

Click to expand...

What is a Earth Leakage (IL) tester? Also you said "turned the dial till the EL tripped out", just curious what you mean and how it prevented him from playing his stereo. Did it trip the circuit breaker that was supplying power to his stereo?

if it's what i'm thinking, it's a high voltage AC power supply with a very low current output and a microammeter. it's used for testing the isolation voltage of power transformers, etc.... sometimes they have a circuit that trips and turns off the output voltage at a predetermined leakage current level, others do not. the ones that don't need to be used carefully, because they can cause the insulation in the transformer under test to break down and damage the transformer. in the US, the standard test voltage is 1500V, but a leakage tester (also known as a HIPOT tester) can usually go up to about 3kV.

Sceadwian said:

The cheapest way to stop people from making loud music at odd hours is to call the cops.
If you're stoned or have anything illegal nearby, do NOT call the cops.

Click to expand...

lol
lol
lol
lol

btw, i had forgotten, this thread gets a Marvin Award!!!!!!!!!
(if you click on the thumbnail, the GIF is animated)

You want to jam his radio, try strawberry. I hear it ruins electronics quite well.
sorry to jump in so late

This will do just exactly what you want. **broken link removed**