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  1. ProfDrK

    magnetron hardwire to coax - possible?

    The tuner is automatic and digital, and it reports forward and reflected power and stub lengths in real-time. Tuner was working perfectly like I said. I wanted an answer about direct magnetron to coax connection, not critique of my experiment that I know already worked. My connectors are 7/16...
  2. ProfDrK

    Resonant frequency of water possible or not?

    I was following that story closely and concur with most points. The media were not helpful nor was the web, but it is not likely possible to couple RF energy by simple absorption in the water. That is why we have 'ionizing' radiation (x-rays for example). But I wanted to add my observation...
  3. ProfDrK

    magnetron hardwire to coax - possible?

    I have a regular 1.3 kW magenetron/launcher/stub tuner/waveguide to coax adapter in series and was dissatisfied with losses. (tuner worked perfectly) I am using the exposed (1/4 wave) coax core as a radiator/antenna for heating within a hole. Can a coax center-lead be connected to the magnetron...
  4. ProfDrK

    convert launcher to cable-to-waveguide adapater??

    Pasternack doesn't have them this big (WR340). Web is woeful poor with pictures. Intent for short term is to make measurements at low power, so arcing issues or mating an oven are not an issue. I plan to have the high power units for high power use. Right now, I need measurements and the coax...
  5. ProfDrK

    convert launcher to cable-to-waveguide adapater??

    I have 2 identical launchers and need 2 identical waveguide to coax adapters (all W340) I need 2 adapters to make dielectric measurements using a network analyser at 2.4 GHz. The retailer claims 10 weeks lead time for the adapters, so I thought I'd make them IF you guys say there wasn't anything...
  6. ProfDrK

    simple readout question of probe in isolator/coupler

    I have two 2.45 GHz isolators, one with sma and the other with N connectors that go to probes in the body of the isolators. Are these probe outputs standard in the industry or can I only use a calibrated meter made by the same company as the isolator? Can I safely (rely-on)adapt from sma to N or...
  7. ProfDrK

    can a bare ended coax cable be called an applicator?

    thanks biff. didn't know name for rarefied gas plasma was multipactor. you exposed my purpose for process. I didn't want damage to coax but did want plasma to raise heating rate to block of material. the material is dielectric and low loss tangent so by vacuum, generate some plasma and as the...
  8. ProfDrK

    can a bare ended coax cable be called an applicator?

    The similarity to the last post below makes me want to add more detail before the idea is critisized and before an actual worthwhile answer is given. I plan to use rigid coax but might try coax cable inside the metal vacuum chamber where it doesn't matter if there is some loss. I want a smaller...
  9. ProfDrK

    can a bare ended coax cable be called an applicator?

    If you take a short length of coax cable on a waveguide to coax adapter (large size coax, tbd), fed by a 1.2 kW 2.45 GHz magnetron and isolator, and trim the end to expose the correct length of center conductor, and then inserted that end into a volume of dielectric material; would the wave...
  10. ProfDrK

    Domestic magnetron to coax adaptor

    tin, my experiences are somewhat parallel to yours working with oven magnetrons and directing their power in different ways. One early lesson I learned was that leaking microwave energy can set off fire alarms. (Just another piece of the kind of advice we are looking for which could never come...
  11. ProfDrK

    magnetron microwave launcher design

    Thank you logbook. I will add this to similar devices I have seen for future purchase. My problem is coupling the output of such a beast (or its little brother) to almost dry soil in situ in order to further dry it. I have several other stipulations, such as compactness, but that is for the...
  12. ProfDrK

    magnetron microwave launcher design

    I unbolt the magnetron from the waveguide fabricated on the oven wall and rebolt it into a comercial aluminum launcher which is wr340 size at one end and wr284 at the other. Its about 6 inches long terminated with a circular flange. The 'probe' passes through a 1.25 inch aperature centered on...
  13. ProfDrK

    can protective grid in door fail during normal use?

    A crack isn't visible in the grid and the 'leak' is gone for now. However, the bulge comment is near phsycic. This oven is operated with the magnetron and powersupply at top and the door hinge at the bottom. This provides me a long throw downwards to heat tall containers. It is conceivable the...
  14. ProfDrK

    magnetron microwave launcher design

    Higgler; Power from the wall socket was measured and is nearly identical whether in the waveguide or the oven. With a working maggie, current draw is unchanged. I can eliminate conductor heating failure since the operation in the oven is repeatable and the temperature levels-out at 90C at power...
  15. ProfDrK

    magnetron microwave launcher design

    logbook, it's tricky. I blame the launcher. Nobody wants to give me that I might be right. I don't have the equipment to prove the launcher SWR is correct. The backspace from the dipole is 1.75 cm, and as far as I know, it should be more like 3.05 cm. This launcher has 3 arrays of small holes...
  16. ProfDrK

    magnetron microwave launcher design

    Sorry biff44, I addressed those points as part of the introduction to the problem. The problem is baffling because 1. the launcher/automatic tuner/15 db horn is operating in a large sheilded room with idle equipment and furniture in it to absorb reflections (that is equivalent of open to the...
  17. ProfDrK

    magnetron microwave launcher design

    Thank you biff44 and Comcokid. Regarding interface to soil, I was aware some reflection might occur, but the soil has only of the order of a percent of water. Importantly, my overheating problem occurs even when there is no load at the exit of the waveguide/horn (whether there is a horn or not)...
  18. ProfDrK

    magnetron microwave launcher design

    I plan to direct the output from an oven magnetron from a launcher/horn combination to dry wet soil as efficiently as possible. I have played with a couple of launchers, but despite an auto tuner showing no reflections, the (aircooled) magnetron overheats (over 100 C in a couple of minutes)...
  19. ProfDrK

    E sector horn for heating

    Am I correct in assuming that if I employ an E sector horn (fed by magnetron) for heating a volume of material, it would do as good a job as if I used a pyramidal horn IF there were no ferritic or other material with magnetic susceptability in my target? Proper tuning and isolator are assumed...
  20. ProfDrK

    can protective grid in door fail during normal use?

    I never thought leakage from a foot away could be measured at a higher level than where the leak occured. Anyway, the seals are not dirty as this is never used for food. As I said, the door seal doesn't leak except where all doors leak (1 mW/cm2) but the signal is high in the middle of the door...

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