Crazy powerful radio transmitter - Page 1
Forum section: electronics / general

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 02, 2017, 12:59:03 am
content: I had a friend talk about an extremely powerful RF circuit that was transformer coupled through a microwave oven transformer apparently it would light up the neon lights under his truck and wonder would this type of circuit most likely be a VCO or if anyone has heard anything similarand it was wired into the truck so the source was very likely 12V dc unless an inverter circuit was used which I doubt

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 02, 2017, 02:14:21 am
content: Microwave oven transformers (MOT) are mains-frequency devices (50Hz or 60Hz). It is unlikely that there is any MOT on this planet that will pass anything remotely resembling "RF".An MOT all by itself will light neon lights. Even when driven with a low-frequency oscillator powered from 12V. Again, no "RF" required here.If he really was driving down the street with a "Crazy powerful radio transmitter" I would advise him to stay clear of FCC agents.

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 02, 2017, 03:33:25 am
content: That funny because he himself said that if I ever a way to construct it, it's construction would only be operated in a Faraday cage then it must have been more likely a HV supply which again I'm confused how he didn't blow up components at this voltage unless external control circuitry was used

author: jh15
author_rank: Frequent Contributor
timestamp: July 02, 2017, 03:41:24 am
content: So, he'll put his truck in a Faraday cage to comply with FCC?

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 02, 2017, 05:06:47 am
content: He didn't I'm unsure if the laws weren't in effect for time period or if it went largely unnoticed for him I however planned on building it myself and then implementing a Faraday cage love the satire though the image that gave me is truly golden lol

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 02, 2017, 06:32:56 am
content: An MOT from North America steps up the 120V mains power to 2000VIf you drive a raw MOT from a 12V chopped signal (converting DC to AC), then it will output roughly 200V, plenty to drive thoseautomotive discharge lamps.Unless you friend can provide a schematic diagram and/or circuit description, I very strongly suspect there is no "RF" involved here. Sounds like a back-woods, mountain-boys tall tale to me. An MOT would be very inefficient (if it would operate at all) at anything above a few hundred Hz.Of course, if there is arcin' and sparkin' going on here, then he may have created a broadband spark-gap transmtter like the kind used in the early 1900s and banned by the FCC perhaps 80-90 years ago.

author: AG6QR
author_rank: Frequent Contributor
timestamp: July 02, 2017, 04:26:35 pm
content: A microwave oven is essentially a radio transmitter, enclosed in a Faraday cage, where the Faraday cage usually also holds food. But the transformer isn't the part that generates RF, the magnetron is the primary device that's responsible for that. In theory, you could harness the magnetron of a microwave to generate a communications transmitter, but you'd have to add some means to modulate it if you wanted to communicate anything useful.But I take issue with the term "crazy powerful". Microwave ovens are rarely above 1-2 kW or so. If you want "crazy powerful", you'll have to do better than that; try something like an RCA 6949 vacuum tube:http://frank.pocnet.net/sheets/049/6/6949.pdfRead the specs and drool. 500kW continuous output. The filament alone takes 1130A at 7.8V, for 8.8kW! Cooling with distilled water required, starting at over 40 gallons per minute for low power use.

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 02, 2017, 05:21:03 pm
content: And Drooooooool I did because I'm not sure but I may have one of those or a smaller version of the triode and serious beard scratch modulating a a magnatron with a spark gap sounds incrediblely simply to do except for I'm not sure where to start with the control circuitrys far as crazy powerful I know microwaves on the order of around 1000watts or so I just never heard of such a design and for most YouTube projects are battery powered so obviously very low power

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 02, 2017, 07:03:57 pm
content: Quote from: AG6QR on July 02, 2017, 04:26:35 pmI think this is my favorite part...Quote

author: WastelandTek
author_rank: Frequent Contributor
timestamp: July 02, 2017, 07:24:16 pm
content: This whole premise smells of infantile BS. To my knowledge no one has yet managed to harness an oven magnetron for communication purposes.That said, there are some very impressive, if totally illegal, mobile setups out there. The search term is "AC sky's the limit." They call these meets "breaks" and it is essentially RF drag racing. The traditional contest frequency is 27.385MHz.Years ago, in the early days of the internet, there was a video floating around I can no longer find of a suburban reputed to be developing some 70KW peak. The video was recorded on a mag tape camcorder at a distance of about 45 feet and at the peak of the run the video actually completely broke up and hints of the AM modulation were audible.They utilize up to 10 large frame Leece Neville alternators (some supposedly use Lexidyne locomotive alternators) driving triodes with handles. Lots of video out there like this. Check out the corona about 50 seconds in.

author: Jr460
author_rank: Regular Contributor
timestamp: July 02, 2017, 08:04:39 pm
content: You haven't seen power until you have taken a tour of an VOA (Voice of America) site while it was in operation.https://en.wikipedia.org/wiki/Voice_of_America_Bethany_Relay_StationThey heated the buildings in the winter with steam from generated from cooling the output tubes.

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 02, 2017, 11:31:48 pm
content: OH MY LORD 250KW and one with 500kw WLW is named worlds largest wattage for a reason only to exceeded by radio Moscow which I'm actually a little scared to see how many watts that thing is operating a 70kw CB actually sounds like something I would build just for fun of course

author: Mosaic
author_rank: Regular Contributor
timestamp: July 11, 2017, 10:17:15 pm
content: Hmm...wondering if it's possible to modulate the Microwave tube to do point to point backhaul microwave for WiFi. A parabolic antenna coupled with a few hundred watts of 2.4Ghz RF could probably reach hundreds of miles.

author: CJay
author_rank: Super Contributor
timestamp: July 12, 2017, 07:04:30 am
content: Quote from: SKHILLBILLYSlures on July 02, 2017, 11:31:48 pmPlease don't, it's possible to hear those aresholes splattered over 70KHz or more and pegging the needle here in the UK, they must wipe out a *huge* portion of HF in the US

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 20, 2017, 01:07:31 am
content: No worries should I ever take up the project I would use proper RF sheilding in order to keep it from leaving my barn and would likely build it just to say I did and better understand the Operation of such a circuit through constructing onePlease don't, it's possible to hear those aresholes splattered over 70KHz or more and pegging the needle here in the UK, they must wipe out a *huge* portion of HF in the US

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: July 20, 2017, 01:24:47 am
content: Quote from: Mosaic on July 11, 2017, 10:17:15 pmis there any way I could use a similar circuit to this that was only a few watts to jam the wifi in my house?

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 20, 2017, 01:44:13 am
content: Quote from: SKHILLBILLYSlures on July 20, 2017, 01:24:47 amis there any way I could use a similar circuit to this that was only a few watts to jam the wifi in my house?There are already (illegal) WiFi and cell phone jammers out there.Or (NOT recommended!) you could defeat the interlock on your microwave oven door and blast 2.4GHz for a few dozen meters. Even with the door closed, I can't use WiFi or BlueTooth within 1m of my microwave.

author: tiger99
author_rank: Newbie
timestamp: August 07, 2017, 10:53:19 pm
content: Please do not do this! High RF fields are extremely dangerous and it amazes me that the idiots in the video were standing as close as they were. Possibly trying to qualify for Darwin awards? Plus there will be serious legal consequences, especially if any innocent person is injured or killed, as is quite likely.In any case, using a magnetron simply to energise a few lights is an incredibly ineffective way of doing it, and it would be impossible to avoid anyone nearby not receiving RF burns. It is very important that the likes of microwave ovens are properly maintained, with no excessive leakage around the door, to avoid serious injury. Allowing the energy to be radiated is way beyond stupid, or even criminal, it is utterly and completely reprehensible and imbecilic, which is why I believe that the original story was not true, or was misunderstood. Had it been true, there would have been a number of serious and probably permanent injuries. You don't recover from being microwaved, the heat is generated internally in whichever body parts are exposed to most of the field, and the cooked flesh and organs are dead, permanently. If they are vital ones, you die. If it is a limb. it will need to be amputated. There are legal limits on RF exposure for a very good reason.The former Soviet Union, not well known as being in the forefront of public safety, set their safety level for microwave exposure very much lower than the US. The EU limits also are lower. There is a reason for that, which you may care to ponder.

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: October 06, 2019, 06:40:32 pm
content: It's definitely waaaayyyy layer for a response butAs i have been informed yes a cell phone jammer can be illegal (but you can still legally purchase one)But as far as the FCC states to my knowledge that very low power transmitters are fine as long as they are only operating on your property and the transmission range doesn't exceed thisIm on 2.5 acres so again I'll ask despite anyone's reluctanceCould i witness a schematic that spits out random 2.4 gigahertz that's very low power

author: Towger
author_rank: Super Contributor
timestamp: October 06, 2019, 07:12:37 pm
content: You can light up a neon tube with a 4w CB, crazy power not required.

author: SKHILLBILLYSlures
author_rank: Regular Contributor
timestamp: October 06, 2019, 07:55:51 pm
content: Well i guess a about year later i got an answer lolSeriously that's cool any youtube fodder on this

author: Jr460
author_rank: Regular Contributor
timestamp: October 06, 2019, 08:02:43 pm
content: Quote from: SKHILLBILLYSlures on July 02, 2017, 11:31:48 pmAnd right next to WLW used to to Voice of America VOA. Very near me. They had several transmitters in that power range. They used the hot water from the tubes to heat the building in winter. I got a tour of the place while it was in operation in later 1970s. All the massive antennas are down and the area is now a park. The transmitter building remains as a museum.