Author Topic: Crazy powerful radio transmitter  (Read 2988 times)

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Offline SKHILLBILLYSlures

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Crazy powerful radio transmitter
« on: July 02, 2017, 10:59:03 AM »
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 similar

and it was wired into the truck so the source was very likely 12V dc unless an inverter circuit was used which I doubt
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Offline Richard Crowley

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Re: Crazy powerful radio transmitter
« Reply #1 on: July 02, 2017, 12:14:21 PM »
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.
 

Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #2 on: July 02, 2017, 01:33:25 PM »
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
« Last Edit: July 02, 2017, 01:35:59 PM by SKHILLBILLYSlures »
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Offline jh15

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Re: Crazy powerful radio transmitter
« Reply #3 on: July 02, 2017, 01:41:24 PM »
So, he'll put his truck in a Faraday cage to comply with FCC?
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Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #4 on: July 02, 2017, 03:06:47 PM »
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
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Offline Richard Crowley

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Re: Crazy powerful radio transmitter
« Reply #5 on: July 02, 2017, 04:32:56 PM »
An MOT from North America steps up the 120V mains power to 2000V

If you drive a raw MOT from a 12V chopped signal (converting DC to AC), then it will output roughly  200V, plenty to drive those
automotive 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.
« Last Edit: July 02, 2017, 04:36:32 PM by Richard Crowley »
 

Offline AG6QR

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Re: Crazy powerful radio transmitter
« Reply #6 on: July 03, 2017, 02:26:35 AM »
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.pdf

Read 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.
 

Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #7 on: July 03, 2017, 03:21:03 AM »
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 circuitry

s 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
« Last Edit: July 03, 2017, 03:23:25 AM by SKHILLBILLYSlures »
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Offline Richard Crowley

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Re: Crazy powerful radio transmitter
« Reply #8 on: July 03, 2017, 05:03:57 AM »
Read 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.

I think this is my favorite part...

Quote
Starting current must never exceed 1700 amperes, even momentarily.
   :bullshit:
 

Offline WastelandTek

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Re: Crazy powerful radio transmitter
« Reply #9 on: July 03, 2017, 05:24:16 AM »
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.

« Last Edit: July 21, 2017, 02:14:19 AM by WastelandTek »
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Offline Jr460

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Re: Crazy powerful radio transmitter
« Reply #10 on: July 03, 2017, 06:04:39 AM »
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_Station

They heated the buildings in the winter with steam from generated from cooling the output tubes.
 

Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #11 on: July 03, 2017, 09:31:48 AM »
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
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Offline Mosaic

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Re: Crazy powerful radio transmitter
« Reply #12 on: July 12, 2017, 08:17:15 AM »
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.

 

Online CJay

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Re: Crazy powerful radio transmitter
« Reply #13 on: July 12, 2017, 05:04:30 PM »
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

Please 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
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Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #14 on: July 20, 2017, 11:07:31 AM »
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 one

Please 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
[/quote]
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Offline SKHILLBILLYSlures

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Re: Crazy powerful radio transmitter
« Reply #15 on: July 20, 2017, 11:24:47 AM »
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.


is there any way I could use a similar circuit to this that was only a few watts to jam the wifi in my house?
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Offline Richard Crowley

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Re: Crazy powerful radio transmitter
« Reply #16 on: July 20, 2017, 11:44:13 AM »
is there any way I could use a similar circuit to this that was only a few watts to jam the wifi in my house?[/quote]
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.
 

Offline tiger99

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Re: Crazy powerful radio transmitter
« Reply #17 on: August 08, 2017, 08:53:19 AM »
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.
 


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