Death-ray for weeds - environmentally friendly?

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Re: Death-ray for weeds - environmentally friendly?

Post by Admin on Tue Aug 06, 2013 4:37 pm

DragonForce wrote:Can you see the headline?  Harry "Flash" SM0VPO trying to establish the wavelength of a blade of grass..... 

Wonder if we could have a full lambda daffodil xD 

http://www.youtube.com/watch?v=LfmrHTdXgK4

Interesting!! Did you know that there was a guy famous, George Cole, who played the character "Flash Harry" in the St. Trinians comedy films?



He used to help the 6th form girls to market the gin they made in the school laboratory. He even took bets on the horses for the head mistress, but he never sold kits Smile 



In one episode the girls set fire to the school. When the fire brigade came they re-connected the firemen's hoses to a petrol tanker. But no-one set fire to the garage door!! That was long before microwave ovens.

BR Harry - SM0VPO

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Re: Death-ray for weeds - environmentally friendly?

Post by DragonForce on Mon Aug 05, 2013 5:05 pm

Can you see the headline?  Harry "Flash" SM0VPO trying to establish the wavelength of a blade of grass..... 

Wonder if we could have a full lambda daffodil xD 

http://www.youtube.com/watch?v=LfmrHTdXgK4

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Re: Death-ray for weeds - environmentally friendly?

Post by Admin on Mon Aug 05, 2013 4:19 pm

Thanks for the link, I will have a look at that later on.

Anything that is useful and chemical is banned here in Sweden so I think I have a good justification for publishing it. It does not poison the soil and is therefore environmentally friendly.

While testing a more "photographable" version of the ray, I sat it on a trolley with a Black-&-Decker workmate holding it all together (the transformer weighs a ton). As I was focusing it and checking the output with a probe on a bit of stick, I noticed the smell of burning Shocked 

It turned out that it was focussed ok, and heating up the garage door inside wooden panel. Wooden garage doors are not micro-wave safe Surprised 

Another thing is that I have tried two dishes and all seem to have poor geometry that disperses the beam - most of the power seems to be lost with dispersion. I have a small (40cm) reflector that was a part of a domestic ceiling lamp. That gives me a much stronger signal from Thor than the "proper" satelite dish, but it is a begger to align - really touchy! I cannot use that for the magnetron since it is so small and it has to be centre-fed. With 800-Watts I need an offset dish. Maybe I should make one.

Just mounting the magnetron upside-down with a catfood-tin as director, I fitted it to the front of the trolley and it burned the grass it went over but takes a bit of time. I think that the soil absorbs power, but the other tests were horisontal (not pointing at soil).

Ok, gotta go now. Got to meet some wonderful people at the Upsalla radio club.

Bye - Harry - SM0VPO

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Link didn't come out...

Post by dave_zap on Sun Jul 28, 2013 9:52 pm

I'll try and insert it again.

servv89pn0aj.sn.sourcedns.com/~gbpprorg/mil/herf1/index.html

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Weed zapper

Post by Dave_zap on Sun Jul 28, 2013 9:43 pm

I wouldn't worry about publishing a weed burner although quite a dangerous one.  Why?  The 'unethical' version of it has been on the internet for years now.



You'll have to copy and paste the address as guests cant post links.
 
At least being site admin you don't get branded a terrorist.  When I asked about making a large RF pulse to direct before, I was put down for it.  As it turns out, I made it myself anyway in the end.

It could be also useful for frying balls at a distance.  I think you know who's balls!

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Re: Death-ray for weeds - environmentally friendly?

Post by Admin on Fri Jun 21, 2013 5:58 pm

DragonForce wrote:Don't forget that you should wear the Flash Gordon outfit whilst photographing death rays. Oh, and the tin foil hat xD

Hmmm. Funnily enough, a young lady once asked me to wear a Flash Gordon outfit, but that was long before microwave ovens were invented Wink.

But seriously, a couple of guys at work think it would be a bit unethical to publish such a project because of the obvious possibilities for misuse. Other guys want to rent me to clear their garden paths, ditches and access roads.

I just found a new use for it, to soften asphalt. Makes it easy to cut with a heavy-duty carpenters knife. I only tried a little section and it makes a lovely neat cut.

BR Harr

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Re: Death-ray for weeds - environmentally friendly?

Post by DragonForce on Thu Jun 20, 2013 1:23 am

Quote:   "At the moment it is somewhat dangerous but as soon as I get it mounted more securely I will post a few pictures. I can always show it heating the pool :-)"


Don't forget that you should wear the Flash Gordon outfit whilst photographing death rays.


Oh, and the tin foil hat xD

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Re: Death-ray for weeds - environmentally friendly?

Post by Admin on Wed Jun 19, 2013 5:39 pm

I am sorry but it is 1L for 30 Euros. But even so here in Sweden they have banned loads of things, for examply Red Bull has to be specially prepared ro remove certain substances. Newcastle Brown Ale has to be reduced from 7.5% to 5.1% alcohol, Polish spirit is reduced from 80% to 40%, and the copper-based paint they use on the hull of boards to prevent barnacles is now totally illegal. ANY weed-killer that poisons soil is now illegal in Sweden.

In France they have wine festivals, in Germany they have beer festivals, but in Sweden they used to have a water festival. Unfortunately someone thought it was too much fun so that was cancelled. Now it is just Gay Pride festivals in Stockholm. There was a pop music festival planned for this week but there were compaints about where "loving couples" could have a little privacy to make love.

But my little 800 Watt death-ray kills weeds beautifully. One problem I did find was that when I assembled the transformer/magnetron on a board there were a few 1000's of volts between the transformer chassis and the magnetron chassis. It could have been dangerous but I never take anything for granted - I use a "de-bollocking stick" to make sure the 10M bleeder resistor in the cap has indeed discharged the capacitor. But a nice heavy common Earth solved that problem and it began lighting flourescent tubes, jamming digital cameras and killing weeds.

I have a few huge trees (over 30m high) that need to come down so I thought of climbing 1/2 way up, fitting the magnetron and running it from a distance. The trees are too high for me to simply cut down as they would hit the house. I tought that using the magnetron with the "bean-tin" nozzel could dry/burn the tree in the middle so it would fold itself down while burning. It would certainly be a lot safer than cutting the tree with me 15m up there.

I have managed to get a lovely grass fire on the slope to the side of the house. Took about 60 seconds to dry and burn the weeds with the sattelite dish at 5 metres distance, and I could keep the dish slowly moving to keep the flames burning :-)

Next winter I will give it a try to get rid of snow. I hate shovelling 1 metre deep snow, especially if it was wet snow that froze.

> What will you use for power?  If you use a battery you would have a pretty heavy rig when finished.

No battery, just a nice long extension lead. I have a few 50m leads so I just plug them in and extend it up to 150m. I also have a power outlet on the lamp post in the middle of the garden. If I wanted to use batteries then I have a couple of 100A/H batteries and a 1.4kW inverter sitting here waiting for the next power cut so Maj-Lis can still have the coffee perculator running :-)

The rig is already rather heavy but the off-centre sattelite dish is mounted upside-down so the magnetron is above the dish and the beam is focussed downwards to the ground. I mounted it on a sack barrow and the magnetron/board supports the dish (not the other way round) because the magnetron/transformer weighs a few kg: quite a bit more than the dish.

If you are really interested in then I pasted some aluminium foil on the dish so I could use a lamp to focus the dish feed-point. It needs to be out about 5cm further away from the dish than the original LNB since the beam "spot" is now about 5 metres in front of the dish. At the moment it is somewhat dangerous but as soon as I get it mounted more securely I will post a few pictures. I can always show it heating the pool :-)

As you can see I split the thread since it was getting a bit off-topic. But I wonder about the ethics of the project. It costs about US$1 per 4 hours use and does not poison the ground, so it is environmentallt friendly. But something like this could be misused. I suppose one of my RF transmitters could be used to block 121.5MHz - it is not the technology that is wrong but the mentality of the user. Has anyone else got thought on this matter?

BR Harry

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Death-ray for weeds - environmentally friendly?

Post by Ivan on Sun Jun 16, 2013 7:16 pm

Hi Harry,
re dish: commonly known formulae become invalid in short distances from the dish. 10 wavelengths is cca 1,2 m in this band, so unexpected behaviour is possible within several metres. I have no clue how to do the maths here.

re Roundup: Maybe another chemical is sold in Sweden than in Czechia ? "Roundup" which I know gets on leaves, migrates inside the plant to the roots and destroys them. All the plant gets dry and dead. The soil is not poisoned, though. Solution 1:40 is enough. It is possible to apply solution 1:5 on leaves of unwanted plants using a brush,in the vicinity of wanted flowers. The former dry, the latter stay untouched. This is not taken from advertisements, it is my personal experience. But yes, it is quite expensive.

VBR from Ivan

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Re: Death-ray for weeds - environmentally friendly?

Post by Jalex2 on Sun Jun 16, 2013 2:57 pm

Hi Harry
 That's an interesting idea. What will you use for power?  If you use a battery you would have a pretty heavy rig when finished. 
I saw a documentary on tv once where a guy used a rig like that and focused it on a test tube of sea water and made more hydrogen than I ever thought possible with that tiny bit of water.
I have repaired lots of microwaves but never thought about doing anything other than that with them. I just never liked to mess with any kind of radiation and never wanted to take any chances with it.

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Re: Death-ray for weeds - environmentally friendly?

Post by Admin on Sun Jun 16, 2013 11:14 am

PoundUp is a very nice product but at 30 euros for a 250ml bottle I think it is very expensive. I would need to use four bottles to kill the grass on the entrance road to my home.

Since RoundUp does not kill the roots then I would have to repeat this every month. 120 euros is more than the cost of a microwave oven, which can do exactly the same job but also kill the roots. This will only need to be repeated once every few months.

So a MW-oven magnetron at the focus of a sattelite reflector is cheaper and does not poison the soil. In addition I have already got a few "customers" lined up who want their gravel drives and paths radiated. I do a 15m drive in an hour and charge 25 Euros. Every Euro is going to the house in Spain that we will buy when I retire :-)

AllI need to do is to make it safe to be carried by hand as the operator would get seriously radiated as it stands at the present.

Final comment, can anyone calculate the output effect using an 800W microwave oven magnetron and a 1.2m parabolic dish? It is not as easy as you think: The magnetron antenna is fited with a 5cm apperture and has been adjusted optically to focus to a spot at 4m distance. It seems that the "spot" is about 20cm diameter but about 2m distance it is still effective and kills the grass in 45 seconds. At 4m it kills grass in about 15 seconds. It also kills down to around 5cm into moist gravel but only about 2cm into soil.

At 2.45GHz the gain of the reflector would be calculated to be a lot higher but at short distances the dispersion must account for a massive gain reduction. Just think, if I could focus to a pencil then I could have an ERP of perhaps 30kW Twisted Evil

BR Harry

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Death ray for weeds - environmentaly friendly?

Post by Ivan on Wed Jun 05, 2013 12:33 pm

Hi Harry,
be careful not to get your car entrance exploding bom I am quite happy I can still buy such nice chemicals like Roundup(TM) in Czechia. It acts on growing plants only, the soil stays OK.

VBR from Ivan

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