...Now for the part that is magic, though it may not seem like it. Teasing something that was designed only for pulse mode into working in CW mode is in this case, quite a trick. Here is one of the power supplies I built...
...you need to make anothe step down transformer to get to the 3.3 volts the magnetron wants for filament power, at 10 amps or so.
...rectify that with shottky diodes, what a pain, and at 10 amps, they need heatsinks too.
...what you do want for this is a constant current type supply for the DC that will do about 4.1 to 4.3 kV and not quite full filament voltage, you want about 3 volts there
...Why this hassle? It's because in a magnetron, running under normal pulsed conditions, builds up electrons during the pulse, and many of them wind up hitting the filament again, heating it up, so even in that mode they don't use the full filament voltage to heat the thing, to compensate. If you try to run one CW, these electrons can just continue to build up and heat the filament further, not to mention that at some point they start inihibiting the oscillations themselves. Luckily, most mass production magnetrons have the magnetic field not quite straight, and this gives the electrons an escape path, spiraling out of the top or bottom of the internal resonator. In fact, if you are unlucky and get a perfect one, you'd have to add a magnetic error (shim) to get that condition, or it won't go CW at all.
...The key is using a much smaller capacitor in the series leg of the voltage doubler, about 1/10 of what was in the oven, and another diode and filter cap to produce DC rather than pulses out of the supply.
...The charge on the output filter cap is lethal! Or close enough, I got zapped by that once when it was up top, and it was pretty bad, so down it goes where I can't touch it by accident.
...there is a 15v supply to run the fan that is strapped to the magnetron to keep it cool, you still need that as the filament power alone will get one hotter than it's specified for, even though we're only pushing 20-50w DC into it, and most of that goes right back out as RF at 2.45 GHz. I used a computer case fan
...The variac is required and the setting is moderately critical. Too high and the thing goes in and out of oscillation as the electrons build up in there, and too low and it's either not enough power to do the job, or it just doesn't go at all. This setting is very near the point where the transformer begins to saturate and draw actual power even at no load
...I do need to add some words about dreaded evil magic, otherwise known as mode hopping in the magnetron. Commerical oven units in general will hae 8 resonators in them, and in real life, they won't all be tuned precisely the same. Combine that with the fact that some will have higher Q than others, and in various circumstances one or a group will determine the precise oscillation frequency, then another at some slightly different frequency. Our cavity adds a ninth resonator. Mostly and surely when the gas isn't lit, it's the highest Q one of them all, and if it's tightly coupled to the tube, it will take over and control the oscillation frequency pretty well. But if that is marginal, you may see the magnetron go in and out of oscillation at our cavity frequency -- it will still be drawing current off its HV supply but the gas won't light off because the high Q of the cavity rejects frequencies it's not tuned to pretty well. In an extreme case, you may have a problem tube and just have to try another, but that hasn't happened here so far, we can always (so far) find a tuning and coupling combo that makes everything happy together, and now we only see any evidence of mode hopping when we put too much power into the magnetron, so one of the oddball tuned resonators in there can become dominant. So, word to the wise, look for the effect and decide what to do about it, likely you'll not notice, tune for max light, and that will be it.
Fig. 6 suggests that the magnetron jumps between discretefrequencies following the natural frequency that shifts with the100 Hz ripple. Individual spectral peaks have bandwidths of theorder of or less than 50 – 100 kHz. Were the magnetron to be runat this operating point from a constant current power supply withzero ripple and after the magnetron’s temperature has stabilized,one would see a single peak.
Quote from: deltaMass on 07/09/2015 07:55 pmQuote from: WarpTech on 07/09/2015 07:31 pm1. For a phase velocity >> c, the group velocity is << c. So F * vg will have a lot more Force with a lot less Power than a photon rocket. So yes, u >> c is very important.The important thing is, Pin = Pout. The vehicle will accelerate dependent on the available input power until relativistic effects start to change the parameters of the problem. It never goes over-unity. That is simply a mis-inerpretation of what "break-even" means.ToddI believe, based on what I wrote above, that you have not made the case for "no power breakeven until v = c". Indeed, we agree that this breakeven speed is substantially less than c if we take your formula for k to be correct and we take the phase velocity to be superluminal. The question which intrigues me is what the value of 'b' might be (u = b*c). Do you have a handle on quantifying this phase velocity value?What can I say, except today I have a better handle on it than I did yesterday, or the day before... I'm learning too! Now, I understand that "break even" means that Pin = Pout, or 100% conversion efficiency. It doesn't mean anything more than that. The phase velocity depends on the dimensions of the frustum and the frequency driving it. There will be more details on that in my forthcoming paper.Todd
Quote from: WarpTech on 07/09/2015 07:31 pm1. For a phase velocity >> c, the group velocity is << c. So F * vg will have a lot more Force with a lot less Power than a photon rocket. So yes, u >> c is very important.The important thing is, Pin = Pout. The vehicle will accelerate dependent on the available input power until relativistic effects start to change the parameters of the problem. It never goes over-unity. That is simply a mis-inerpretation of what "break-even" means.ToddI believe, based on what I wrote above, that you have not made the case for "no power breakeven until v = c". Indeed, we agree that this breakeven speed is substantially less than c if we take your formula for k to be correct and we take the phase velocity to be superluminal. The question which intrigues me is what the value of 'b' might be (u = b*c). Do you have a handle on quantifying this phase velocity value?
1. For a phase velocity >> c, the group velocity is << c. So F * vg will have a lot more Force with a lot less Power than a photon rocket. So yes, u >> c is very important.The important thing is, Pin = Pout. The vehicle will accelerate dependent on the available input power until relativistic effects start to change the parameters of the problem. It never goes over-unity. That is simply a mis-inerpretation of what "break-even" means.Todd
Martin Tajmar - AAIA presentation this month - his possible presentation notes - FYI drbagelbites:http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/Biefeld-Brown%20Effect%20AIAA%20Journal%20Revised.pdfWorth reading as his 2004 paper deals with The Biefeld-Brown Effect: Misinterpretation of Corona WindPhenomenaIOW, "1. The separation of the plates of the capacitor: the closer the plates, the greater the effect.2. The dielectric strength of the material between the electrodes: the higher the strength, the greater the effect.3. The area of the conductors: the greater the area, the greater effect.4. The voltage difference between the plates: the greater the voltage, the greater effect.5. The mass of the dielectric material; the greater the mass, the greater the effect."Shawyers frustum appeared to have an insulated larger frustum plate, maybe both. In effect, these plates might have been charged electrodes creating "corona wind". Regardless, might be worth reading before attending his presentation.
Re rfmwguy post #3776“I hope all supporters and detractors drop you a couple of bucks for giving it a go. Posting is cheap...building is not.”Just want to let all concerned, especially SeeShells and all the rest who are ‘putting their money where their hopes are’, that in spite of my incessant whining (opinion—would be happy to be proven wrong) about the horrors of oven magnetrons as frustum drivers I am VERY firmly in the supporter camp. As I said before, if any of the DIY’ers are in the Northern VA/DC/Suburban MD area there is at least some possibility that I may be able to get them access to top of the line microwave test equipment, including broadband amplifiers (not magnetrons) in the +40/+50 dBm range.
Quote from: WarpTech on 07/09/2015 09:12 pmQuote from: deltaMass on 07/09/2015 07:55 pmQuote from: WarpTech on 07/09/2015 07:31 pm1. For a phase velocity >> c, the group velocity is << c. So F * vg will have a lot more Force with a lot less Power than a photon rocket. So yes, u >> c is very important.The important thing is, Pin = Pout. The vehicle will accelerate dependent on the available input power until relativistic effects start to change the parameters of the problem. It never goes over-unity. That is simply a mis-inerpretation of what "break-even" means.ToddI believe, based on what I wrote above, that you have not made the case for "no power breakeven until v = c". Indeed, we agree that this breakeven speed is substantially less than c if we take your formula for k to be correct and we take the phase velocity to be superluminal. The question which intrigues me is what the value of 'b' might be (u = b*c). Do you have a handle on quantifying this phase velocity value?What can I say, except today I have a better handle on it than I did yesterday, or the day before... I'm learning too! Now, I understand that "break even" means that Pin = Pout, or 100% conversion efficiency. It doesn't mean anything more than that. The phase velocity depends on the dimensions of the frustum and the frequency driving it. There will be more details on that in my forthcoming paper.ToddPhase velocity + group velocity = 2c. In a waveguide, group velocity is below 1c and phase velocity is therefore above 1c. As such nothing in a waveguide moves at phase velocity or greater than 1c. Everything in a waveguide moves at group velocity or below 1c.Outside a waveguide group velocity = phase velocity = 1c.
Quote from: Rodal on 07/09/2015 06:23 pmQuote from: Ricvil on 07/09/2015 06:18 pm...So the real cavity has spherical or plane taps?Thanks. Excellent analysis. NASA COMSOL FEA found some weird modes also that were a mixture, using plane ends. Most of the researchers have used FLAT ends on their experiments with truncated cones.All NASA experiments have had flat ends. Some of Shawyer''s have had flat ends, from what I recall, according to TheTraveller, Shawyer's FlightThruster has spherical ends.Prof. Yang's have flat ends.Iulian Berca has flat ends.Baby EM Drive has flat ends.The exact solution I have been using uses spherical ends, when approximating a flat end natural frequency I calculate the geometry that has spherical ends halfway between the circumscribed and the inscribed circles (that came close to NASA's COMSOL FEA analysis of all the modes between 0.8 and 2.6 MHz for.Meep models have been using flat ends on conical cavities.I keep thinking about flat versus curved. You can get a higher Q shaping the cavity to the spherical wave shape, but peaking the Q will also open the door to more sensitivity to thermal expansion effects thereby dropping the Q in unwanted waveforms and patterns that almost are uncontrolled and sure to be disruptive. At higher powers it could be a detrimental effect as the copper frustum warpage changes from varying heat signatures in the copper.A flat plat will give a Q oh let's say 50-90k and might offer a more forgiving environment.Shell
Quote from: Ricvil on 07/09/2015 06:18 pm...So the real cavity has spherical or plane taps?Thanks. Excellent analysis. NASA COMSOL FEA found some weird modes also that were a mixture, using plane ends. Most of the researchers have used FLAT ends on their experiments with truncated cones.All NASA experiments have had flat ends. Some of Shawyer''s have had flat ends, from what I recall, according to TheTraveller, Shawyer's FlightThruster has spherical ends.Prof. Yang's have flat ends.Iulian Berca has flat ends.Baby EM Drive has flat ends.The exact solution I have been using uses spherical ends, when approximating a flat end natural frequency I calculate the geometry that has spherical ends halfway between the circumscribed and the inscribed circles (that came close to NASA's COMSOL FEA analysis of all the modes between 0.8 and 2.6 MHz for.Meep models have been using flat ends on conical cavities.
...So the real cavity has spherical or plane taps?
Quote from: BL on 07/09/2015 07:58 pmRe rfmwguy post #3776“I hope all supporters and detractors drop you a couple of bucks for giving it a go. Posting is cheap...building is not.”Just want to let all concerned, especially SeeShells and all the rest who are ‘putting their money where their hopes are’, that in spite of my incessant whining (opinion—would be happy to be proven wrong) about the horrors of oven magnetrons as frustum drivers I am VERY firmly in the supporter camp. As I said before, if any of the DIY’ers are in the Northern VA/DC/Suburban MD area there is at least some possibility that I may be able to get them access to top of the line microwave test equipment, including broadband amplifiers (not magnetrons) in the +40/+50 dBm range. Once i get my test rig running, I plan to do a bulk purchase of the 100W Rf amps my mate found for me. Maybe like $100 + shipping.Have shared the link, so others can jump in before I get my bulk buy going.With this amp and a $100 1kHz step Rf generator you can put 100Ws of pure narrow band Rf energy right in the centre of the EMDrives bandwidth. End result is you get all that lovely 100Ws of narrow band Rf INSIDE the cavity and not being rejected and turned into heat.KISS engineering.
Quote from: TheTraveller on 07/09/2015 07:54 amThe Chinese may have figured out how to make a cavity with a Q of 117,500 using flat end plates.As per the attachment they build in a short section, at each end of the tapered wave guide, of constant diameter circular waveguide that allows the spherical waves in the tapered portion of the cavity to transition from/to a planar wave that will generate no phase distortion as it bounces off the flat end plate.Very clever.The drawings also show how they do impedance matching.See attachment.I now know my 100,000 Q goal is obtainable. Yea!It appears to be a double-tuned circuit; two cavities coupled through a small aperture. I read the NWPU paper a month ago or so. If I understand Shawyer's theory right, the only EM momentum that matters is in the frustrum, and the Q that matters is the Q of the frustrum, not an additional filter cavity that is used to couple energy to it.But maybe it helps slow the group velocity in the frustrum in some way.Anyways, is it the Q of the frustrum that is so high, or is it the combination of the two filter cavities that is?
The Chinese may have figured out how to make a cavity with a Q of 117,500 using flat end plates.As per the attachment they build in a short section, at each end of the tapered wave guide, of constant diameter circular waveguide that allows the spherical waves in the tapered portion of the cavity to transition from/to a planar wave that will generate no phase distortion as it bounces off the flat end plate.Very clever.The drawings also show how they do impedance matching.See attachment.I now know my 100,000 Q goal is obtainable. Yea!
Quote from: TheTraveller on 07/09/2015 12:00 pmQuote from: Rodal on 07/09/2015 11:55 amQuote from: TheTraveller on 07/09/2015 07:54 amThe Chinese may have figured out how to make a cavity with a Q of 117,500 using flat end plates.As per the attachment they build in a short section, at each end of the tapered wave guide, of constant diameter circular waveguide that allows the spherical waves in the tapered portion of the cavity to transition from/to a planar wave that will generate no phase distortion as it bounces off the flat end plate.Very clever.The drawings also show how they do impedance matching.See attachment.I now know my 100,000 Q goal is obtainable. Yea!If you draw a horizontal axis through the middle of the waveguide in the picture you show, what does the waveguide opening into the cavity on the plane perpendicular to that axis look like?In other words, what does the other view look like?It would be nice if we could guesstimate what the waveguide opening aspect ratio is, compared to the lateral cavity dimensionsMore info is in the paper, which is in Chinese. Attached.I don't think the drawing is dimensionally correct.That was very hard to read. there are gems of information within the mix of translations and your right I like the endplates too.Shell
Quote from: Rodal on 07/09/2015 11:55 amQuote from: TheTraveller on 07/09/2015 07:54 amThe Chinese may have figured out how to make a cavity with a Q of 117,500 using flat end plates.As per the attachment they build in a short section, at each end of the tapered wave guide, of constant diameter circular waveguide that allows the spherical waves in the tapered portion of the cavity to transition from/to a planar wave that will generate no phase distortion as it bounces off the flat end plate.Very clever.The drawings also show how they do impedance matching.See attachment.I now know my 100,000 Q goal is obtainable. Yea!If you draw a horizontal axis through the middle of the waveguide in the picture you show, what does the waveguide opening into the cavity on the plane perpendicular to that axis look like?In other words, what does the other view look like?It would be nice if we could guesstimate what the waveguide opening aspect ratio is, compared to the lateral cavity dimensionsMore info is in the paper, which is in Chinese. Attached.I don't think the drawing is dimensionally correct.
Quote from: TheTraveller on 07/09/2015 07:54 amThe Chinese may have figured out how to make a cavity with a Q of 117,500 using flat end plates.As per the attachment they build in a short section, at each end of the tapered wave guide, of constant diameter circular waveguide that allows the spherical waves in the tapered portion of the cavity to transition from/to a planar wave that will generate no phase distortion as it bounces off the flat end plate.Very clever.The drawings also show how they do impedance matching.See attachment.I now know my 100,000 Q goal is obtainable. Yea!If you draw a horizontal axis through the middle of the waveguide in the picture you show, what does the waveguide opening into the cavity on the plane perpendicular to that axis look like?In other words, what does the other view look like?It would be nice if we could guesstimate what the waveguide opening aspect ratio is, compared to the lateral cavity dimensions
I really don't like this, to ask. I've always forged my own path through the years with very little help and built businesses in industries where a billion spent is sometimes a drop in the bucket.Totaling up what the costs I'm facing it became clear that with the little I get on retirement I can't do it in the time frame needed. I guess I'm asking for a little help and only if you can.I'm so driven to see real data from these test and to add to the pool of knowledge, I have to swallow my pride and ask. http://www.gofundme.com/yy7yz3kThank you all for your support, your ideas and most of all sharing a dream.Shell
Quote from: rfmwguy on 07/09/2015 08:04 pmMartin Tajmar - AAIA presentation this month - his possible presentation notes - FYI drbagelbites:http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/Biefeld-Brown%20Effect%20AIAA%20Journal%20Revised.pdfWorth reading as his 2004 paper deals with The Biefeld-Brown Effect: Misinterpretation of Corona WindPhenomenaIOW, "1. The separation of the plates of the capacitor: the closer the plates, the greater the effect.2. The dielectric strength of the material between the electrodes: the higher the strength, the greater the effect.3. The area of the conductors: the greater the area, the greater effect.4. The voltage difference between the plates: the greater the voltage, the greater effect.5. The mass of the dielectric material; the greater the mass, the greater the effect."Shawyers frustum appeared to have an insulated larger frustum plate, maybe both. In effect, these plates might have been charged electrodes creating "corona wind". Regardless, might be worth reading before attending his presentation.The end plates are not isolated. They are electrically connected to the conic side walls.
Quote from: SeeShells on 07/09/2015 04:16 pmI really don't like this, to ask. I've always forged my own path through the years with very little help and built businesses in industries where a billion spent is sometimes a drop in the bucket.Totaling up what the costs I'm facing it became clear that with the little I get on retirement I can't do it in the time frame needed. I guess I'm asking for a little help and only if you can.I'm so driven to see real data from these test and to add to the pool of knowledge, I have to swallow my pride and ask. http://www.gofundme.com/yy7yz3kThank you all for your support, your ideas and most of all sharing a dream.ShellIf you would like to verify my test results, I'll gradly send you one of my EMDrives and the 100W Rf amp, Rf gen and frequency tracking system at no cost. I'll even pay shipping both ways. You will need to build the rotary test system but that should be simple for you.Us retired engineers need to stick together.
Quote from: TheTraveller on 07/09/2015 10:45 pmQuote from: rfmwguy on 07/09/2015 08:04 pmMartin Tajmar - AAIA presentation this month - his possible presentation notes - FYI drbagelbites:http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/Biefeld-Brown%20Effect%20AIAA%20Journal%20Revised.pdfWorth reading as his 2004 paper deals with The Biefeld-Brown Effect: Misinterpretation of Corona WindPhenomenaIOW, "1. The separation of the plates of the capacitor: the closer the plates, the greater the effect.2. The dielectric strength of the material between the electrodes: the higher the strength, the greater the effect.3. The area of the conductors: the greater the area, the greater effect.4. The voltage difference between the plates: the greater the voltage, the greater effect.5. The mass of the dielectric material; the greater the mass, the greater the effect."Shawyers frustum appeared to have an insulated larger frustum plate, maybe both. In effect, these plates might have been charged electrodes creating "corona wind". Regardless, might be worth reading before attending his presentation.The end plates are not isolated. They are electrically connected to the conic side walls.Mr. T, please ask whomever you need to accurately describe the material that is prohibiting metal to metal contact of the end plates to the frustum. Thanks.
Quote from: TheTraveller on 07/09/2015 11:44 pmQuote from: SeeShells on 07/09/2015 04:16 pmI really don't like this, to ask. I've always forged my own path through the years with very little help and built businesses in industries where a billion spent is sometimes a drop in the bucket.Totaling up what the costs I'm facing it became clear that with the little I get on retirement I can't do it in the time frame needed. I guess I'm asking for a little help and only if you can.I'm so driven to see real data from these test and to add to the pool of knowledge, I have to swallow my pride and ask. http://www.gofundme.com/yy7yz3kThank you all for your support, your ideas and most of all sharing a dream.ShellIf you would like to verify my test results, I'll gradly send you one of my EMDrives and the 100W Rf amp, Rf gen and frequency tracking system at no cost. I'll even pay shipping both ways. You will need to build the rotary test system but that should be simple for you.Us retired engineers need to stick together.Who says I retired ... lol. Working harder now. I'll tell you what after all is said and done and we have made our tests, we'll swap. Deal? I'll test yours on my beam and you test mine on your carousel. Great comparison I think.Shell
Quote from: rfmwguy on 07/09/2015 11:46 pmQuote from: TheTraveller on 07/09/2015 10:45 pmQuote from: rfmwguy on 07/09/2015 08:04 pmMartin Tajmar - AAIA presentation this month - his possible presentation notes - FYI drbagelbites:http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/Biefeld-Brown%20Effect%20AIAA%20Journal%20Revised.pdfWorth reading as his 2004 paper deals with The Biefeld-Brown Effect: Misinterpretation of Corona WindPhenomenaIOW, "1. The separation of the plates of the capacitor: the closer the plates, the greater the effect.2. The dielectric strength of the material between the electrodes: the higher the strength, the greater the effect.3. The area of the conductors: the greater the area, the greater effect.4. The voltage difference between the plates: the greater the voltage, the greater effect.5. The mass of the dielectric material; the greater the mass, the greater the effect."Shawyers frustum appeared to have an insulated larger frustum plate, maybe both. In effect, these plates might have been charged electrodes creating "corona wind". Regardless, might be worth reading before attending his presentation.The end plates are not isolated. They are electrically connected to the conic side walls.Mr. T, please ask whomever you need to accurately describe the material that is prohibiting metal to metal contact of the end plates to the frustum. Thanks.Do you think every bolt between the end flanges and the end plates are electrically isolated?Like my design, there is a air tight gasket, I use an O ring. Inside the gasket, the machined side wall end contacts the machined end plate. Additionally the many bolts provide electrical conductivity between the side walls and the end plates.
[...]What can I say, except today I have a better handle on it than I did yesterday, or the day before... I'm learning too! Now, I understand that "break even" means that Pin = Pout, or 100% conversion efficiency. It doesn't mean anything more than that. [...]
Quote from: TheTraveller on 07/09/2015 11:54 pmQuote from: rfmwguy on 07/09/2015 11:46 pmQuote from: TheTraveller on 07/09/2015 10:45 pmQuote from: rfmwguy on 07/09/2015 08:04 pmMartin Tajmar - AAIA presentation this month - his possible presentation notes - FYI drbagelbites:http://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/rfs/forschung/folder.2007-08-21.5231434330/ag_raumfahrtantriebe/Biefeld-Brown%20Effect%20AIAA%20Journal%20Revised.pdfWorth reading as his 2004 paper deals with The Biefeld-Brown Effect: Misinterpretation of Corona WindPhenomenaIOW, "1. The separation of the plates of the capacitor: the closer the plates, the greater the effect.2. The dielectric strength of the material between the electrodes: the higher the strength, the greater the effect.3. The area of the conductors: the greater the area, the greater effect.4. The voltage difference between the plates: the greater the voltage, the greater effect.5. The mass of the dielectric material; the greater the mass, the greater the effect."Shawyers frustum appeared to have an insulated larger frustum plate, maybe both. In effect, these plates might have been charged electrodes creating "corona wind". Regardless, might be worth reading before attending his presentation.The end plates are not isolated. They are electrically connected to the conic side walls.Mr. T, please ask whomever you need to accurately describe the material that is prohibiting metal to metal contact of the end plates to the frustum. Thanks.Do you think every bolt between the end flanges and the end plates are electrically isolated?Like my design, there is a air tight gasket, I use an O ring. Inside the gasket, the machined side wall end contacts the machined end plate. Additionally the many bolts provide electrical conductivity between the side walls and the end plates.So, you do not know what the gasket material is? Is it an insulator or dielectric material?
Phase velocity + group velocity = 2c.
Quote from: TheTraveller on 07/09/2015 10:38 pmPhase velocity + group velocity = 2c. Wrong