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Author: Subject: Adjusting the wavelength, houshold microwave.
Hermes_Trismegistus
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[*] posted on 3-3-2005 at 13:42
Adjusting the wavelength, houshold microwave.


Anyone know how to adjust the emitter on a household microwave?



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Twospoons
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[*] posted on 3-3-2005 at 14:25


Don't even try. Its a function of the size of the cavities inside the magnetron.

Useful link

[Edited on 3-3-2005 by Twospoons]
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[*] posted on 8-3-2005 at 21:33


to produce infra red the distance has to be a atom thick, longer it is small freq it is.
imagation a rod, the top is postive the bottom is neg, they change from postive to negitive, the long it is the more time it takes to change.

These is AM/FM theory ,to get microwave freq migth use the heat temapure theory?
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[*] posted on 2-4-2005 at 00:35


Quote:
Originally posted by Hermes_Trismegistus
Anyone know how to adjust the emitter on a household microwave?



You mean adjust the "emission".
It is possible through these methods I know of:
Pulling - Varying the SWR varies output centre frequency. The curve is usually documented in the spec sheet.
Pushing - Varying the anode voltage/current allows for a limited control of output centre frequency.
Magnetic susceptibility - Varying the impinging magnetic field around the core can also affect output centre.
Cavity tuning - Tricky, but apparently it works. A method of adding cavity-based tuning adjustment to a magnetron designed without said adjustment. Requires engineering expertise due to the L/C relationships inside each cavity. Basically introduces set-screws into certain cavities.

Even though it is possible, how far did you want to shift the centre frequency? If it's 5Mhz, it is probably practical. If you want 2450->3250, forget it.
Remember you will probably need a spectrum analyser to see what you are doing, otherwise you will have no idea if your fiddling is changing anything.
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[*] posted on 2-4-2005 at 05:27


If u could successfully adjust the wavelength of the magnetron output you shouldnt use it in the same microwave chamber it was originally designed for. The microwave oven itself is specifically designed for the specific frequency o/p of the magnetron. Any deviance from this frequency could cause resonance or harmful radiation leakage. If you don't have the appropriate testing equipment, you should shelve the idea until you do.



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chloric1
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[*] posted on 2-4-2005 at 18:29
ABSOLUTELY


Froot could not be more right. Microwaves are some dangerous waves. Wanna cook your gonads?!



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[*] posted on 2-4-2005 at 20:16


I have read that burning yourself with microwaves is just like burning yourself with a hot surface... with one exception. Microwaves arent blocked very well by your tissues. So instead of burning off a thin layer of your skin, your burning your skin, muscle, connecting tissue, ect. By the time you know your being burned you may have very bad internal injury. I'm sure nobody wants a pair of well cooked testicles (well nobody normal anyway).
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12AX7
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[*] posted on 2-4-2005 at 23:30


MMM, ROCKY MOUNTAIN OYSTERS! :D

Eyeballs are a more serious target of loose microwaves because you don't have much temperature sensation inside the fluid-filled things.

Microwaves penetrate maybe an inch, not much deeper AFAIK, so your skin and most muscle is at risk; your organs and bones (except for feet, forearms and hands) should be okay. To something person-sized, microwaves should be pretty line-of-sight and easily shadowed, so if you are facing an emitter, your back won't get hot. It probably goes around fingers and arms though (diffraction around objects near the wavelength).

Anecdote: I've heard tales of soldiers downrange asking the radar operator to point the beam at them... apparently at the right distance (1000' or so?) it only keeps you warm, not cooking anything (i.e. dissipation equals input power, maybe 100 or 200W over the cross section of a person).

Tim
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[*] posted on 12-4-2005 at 07:02


"OMG don't touch it, radiation, death, bad!"
People fear what they don't understand.
'Microwave' is a term given to the relatively (at the time of coining) short wavelength of these sorts of frequencies. It's a loose term but 1000 Mhz+ has been bandied about as a qualifier. Practical limits means 50Ghz is as high as anyone reading this is ever going to see. Using this definition, microwaves are just RF. The only known danger from acute exposure to microwave emissions is its direct heating effect. Generally speaking the heating effects of RF become more apparent as you decrease the wavelength, though direct RF burns are possible at any frequency. It's energy. Domestic magnetrons emit a lot of it, and at short wavelength. If you expose yourself to it in an unsafe manner, it will burn.
RF doesn't "fry your gonads" any more than working with Pb in your favourite priming compound "mushes your brain".

(Reproductive organs are sensitive to 'ionizing' radiation. Don't make the mistake of seeing "radiation" and thinking "nuclear". Research shows RF radiation can reduce sperm quality and quantity through heating of testicles but that's all. So if you insist on getting an exposure burn, stick your hand in front of the aperture and not your nuts. Watch your eyes tho.)

Yeah, anyway with RF and safety, skip the FUD. It's the same as with anything potentially dangerous. Employ stupidity and carelessness as skills in your endeavours, and reap the ill rewards. Or use a bit of sense, think about what you're doing, and have a lot of fun and learn while you're at it.
Just ensure you do your homework, understand the subject at hand (especially any potential health threats), take all practical precautions, be careful, use your head and you'll be fine. Basically don't be afraid to experiment - but be respectful of your subject.
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