Folks, I found this document a number of years ago, skimmed though it then put it away on my HD. Dusted it off today, and here I am.
What is this? IS it really what it says it is?
http://72.52.208.92/~gbpprorg/mil/herf/magnetron_amplifier.pdf
It says 30db of gain. How can this be? Can this be a low noise audio amplifier or not? Any ideas?
What is this? IS it really what it says it is?
http://72.52.208.92/~gbpprorg/mil/herf/magnetron_amplifier.pdf
It says 30db of gain. How can this be? Can this be a low noise audio amplifier or not? Any ideas?
The magnetron is a narrow-band amplifier, with the frequency range set by the mechanical features of the valve i.e. a 2.4GHz magnetron can only amplify 2.4GHz. A 1kHz magnetron would have to be roughly 2.4million times bigger!
"Low noise" in this context means low noise as a transmitter, not necessarily low noise as a receiver. People don't use magnetrons as receiver preamplifiers!
30dB gain is nothing special. An ECC83 can give a gain approaching 40dB, EF86 even higher. I'm not sure what all the excitement is about.
"Low noise" in this context means low noise as a transmitter, not necessarily low noise as a receiver. People don't use magnetrons as receiver preamplifiers!
30dB gain is nothing special. An ECC83 can give a gain approaching 40dB, EF86 even higher. I'm not sure what all the excitement is about.
An ECC83 or EF86 can not produce any gain at all in the 2.4 GHz region, nor could it produce 500+ watts of power. The magnetron is designed to be a self oscillating power source useful in radar and RF heating (microwave oven). This is the first time I have heard of one being used as an amplifier. Even today 500 watts of power at 2.4 GHz would require several hundreds of dollars worth of silicon, GaAs or GaN.
As stated, not useful at all for audio though.
Yes, I was surprised at a magnetron being used as an amplifier. It seems the author uses it as a locked oscillator via a directional coupler.
I was not suggesting that ECC83 could be used at 2.4GHz, just that audio gain of 30dB is unremarkable. Maybe I misunderstood the "wow!" factor in the original post?
I was not suggesting that ECC83 could be used at 2.4GHz, just that audio gain of 30dB is unremarkable. Maybe I misunderstood the "wow!" factor in the original post?
It would seem to really be what it says it is. However, it has no audio applications at all. Although, if you could remove the magnet from a magnetron you might be able to use it as a single ended diode. That's about the extent of it.
It isn't anything you'd want to fool with. The frequency mentioned here, 2.4GHz, is right in the middle of aviation frequencies. Though the FCC has been an absolutely incompetent and useless gov't agency, for the past 30 years. It has existed mainly as a source of patronage jobs (Colin Powel's son was once its head, though his radio experience was nil) it refuses to enforce illegal fish net buoys (exceeding legal power limits, and operating well off-frequency -- these things have totally ruined the 180M ham band completely) that are openly sold in virtually every fishing supply store up and down the West Coast, and the US of A is the only developed country in the entire world without a long wave ham allocation. You can get away with running "pirate", "illegal" radio equipment and they won't do anything about it. The FAA, on the other hand, gets real fussy if you start screwing around with their frequencies.
Fire that up, and you can be sure that the men in black suits will come a-callin'.
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nothing unremarkable for audio
Wow (walk or wilt ) 500w at 2.4 ghz nasty stuff.
there is somwhere on the web a guy that built one of those magnatron RF amplifiers and then connected it to a 30 db parabolic dish if i remmember it only had a beamwidth of 8 degrees. WOW!!!!.
There is also an artical by the evil genius about constructing a device from a magnatron that will destroy your hifi from a moderate distance away . OK STOP WORRYING it will only harm your gear if it is switched on.
Regards Mad Mark😀
Wow (walk or wilt ) 500w at 2.4 ghz nasty stuff.
there is somwhere on the web a guy that built one of those magnatron RF amplifiers and then connected it to a 30 db parabolic dish if i remmember it only had a beamwidth of 8 degrees. WOW!!!!.
There is also an artical by the evil genius about constructing a device from a magnatron that will destroy your hifi from a moderate distance away . OK STOP WORRYING it will only harm your gear if it is switched on.
Regards Mad Mark😀
Could you modulate it, rectify the output and filter out the RF, leaving a beautiful intact audio signal? Blindness may be an operating hazard...
The frequency of operation of all microwave ovens is 2.45GHz +/- 50 MHz. This is in the ISM (industrial scientific medical) band for that reason. A leaky microwave oven will not cause interference to any licensed service except amateur radio since many ham radio bands are coincident with ISM bands. 902 -928 MHz and 2304 - 2450 MHz are examples.
This practice isn't too uncommon amongst EME (amateur radio moonbounce) guys. There was an article published in a ham radio magazine (QST maybe) in the mid 1980's that showed how to control the frequency of oscillation of a magnetron and achieve FM modulation. I built that setup (using two 6JE6C's to control magnetron current) and got it to work. I installed the magnetron into a coffee can feedhorn and mounted it in front of a 12 foot TV satellite dish. Attempts to bounce a signal off of the moon were not successful. I now understand that the bandwith of an FM signal was far too wide for that type of communication. I still have the magnetron device somewhere. Magnetrons operate in the 2KV+ range. Don't even think of opening a microwave oven unless you understand the voltages involved.
It is now possible to find surplus cellular equipment for use in this frequency range and 200 watts at 2304 MHz is available on Ebay. I am building a 1200 watt station for 902 MHz using surplus cellular equipment.
Oh yeah I know that thing!!..............My instructor in Microwaves...An ex-Air-Force guy told me of him & his buddies goofing with the on-base Radar systems....They took one of the giant dishes, took it off-line swung it around, pointed it down to the ground & lit up some flourescent lights in an office several hundred feet away. Fun, fun, fun.........
____________________________________________________Rick..........
____________________________________________________Rick..........
Watch out for those microwaves 2.4gHz just happens to be the resonant frequency of water. Also if you are thinking of starting a family in the future extra wow is required.
It is also possible to cook other spherical objects, namely your eyes. I understand that when cooked, the transparent bits turn white like an egg does. Permanent blindness is the result. Don't mess with high power microwaves!
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