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Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
For some time I've been toying with the idea of experimenting with magnetrons.
Obviously, these are/can be dangerous, so I want to reduce the risks as much as possible for my initial 'trials'.
I'm thinking, if I take a complete microwave oven circuit and replace the ~1 microfarad capacitor with a 0.01 microfarad capacitor, this will reduce the power from ~1000 Watts to ~10 Watts.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I did read that someone had 'replaced the 'series capacitor' with a smaller one, in order to run the magnetron in CW mode' (Doug Coulter, coultersmithing.com), but I think the one he used was around a third of the capacitance of the original.
It took me a while to realise what he meant by 'series capacitor'. I always understood it was part of the voltage doubler circuit.
I'm just extrapolating this to it's logical conclusion, if it is small enough, as well as being able to run the magnetron CW, it will be 'safe'?
EDIT: ie, you could regulate the output of the magnetron by using a variable capacitor.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Ash Small wrote ...
For some time I've been toying with the idea of experimenting with magnetrons.
Obviously, these are/can be dangerous, so I want to reduce the risks as much as possible for my initial 'trials'.
I'm thinking, if I take a complete microwave oven circuit and replace the ~1 microfarad capacitor with a 0.01 microfarad capacitor, this will reduce the power from ~1000 Watts to ~10 Watts.
Will this make it 'relatively' safe?
Any comments or suggestions?
Perhaps you should think of health risks being proportional to power density rather than overall system power. Might not a focused beam of 10W be more hazardous than a diffuse emission of 1kW?
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
You have a very valid point, PM. The 'containment system' used by Doug, Carl Willis and others has two apertures 1/2 inch to 3/4 inch or so, where the quartz tubing enters and exits the shielding. (At least, as far as my present understanding goes, and from the photos I've seen)
This presumably allows the microwave radiation to escape. (Although I understand that microwave radiation (RF) doesn't escape through 'holes', but does escape through 'slits', I believe this phenomenon is related to wavelength, but I'm not certain)
These are some of the reasons why I'm asking for comments (This is an 'electromagnetic radiation' forum)
EDIT: I apologise if this post seems 'vague', I'll be sober in the morning.
EDIT 2: What precautions do you suggest I take to avoid this scenario, PM?
EDIT 3: I'm planning to obtain a microwave leak meter thingy.....any other suggestions?
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
I would power the filament from a separate transformer and use a variac to control the one providing the HV.
I know a guy who has used a magnetron as a hand warmer, it's a radio transmitter, not ionizing radiation, but I would still advise caution. I've never received a serious RF burn, but I hear they're extremely painful and a magnetron is certainly capable.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Ash Small wrote ...
You have a very valid point, PM. The 'containment system' used by Doug, Carl Willis and others has two apertures 1/2 inch to 3/4 inch or so, where the quartz tubing enters and exits the shielding. (At least, as far as my present understanding goes, and from the photos I've seen)
This presumably allows the microwave radiation to escape. (Although I understand that microwave radiation (RF) doesn't escape through 'holes', but does escape through 'slits', I believe this phenomenon is related to wavelength, but I'm not certain)
These are some of the reasons why I'm asking for comments (This is an 'electromagnetic radiation' forum)
EDIT: I apologise if this post seems 'vague', I'll be sober in the morning.
EDIT 2: What precautions do you suggest I take to avoid this scenario, PM?
EDIT 3: I'm planning to obtain a microwave leak meter thingy.....any other suggestions?
Hi Ash, you may find this basic intro to slotted waveguides helpful:
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Thanks, PM. This page from the guide you linked to seems to contain some useful info relevant to this project:
Most of the rest seems to relate to radar arrays (I think)
EDIT: This is a link to Doug's page on the subject. It may give you a better idea of what I'm hoping to achieve. (I believe it's been added to since I last read it)
BTW, I'm not planning on ionizing deuterium. I'm more interested in protons, and some other plasmas.
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Basic Magnetron Question
