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  • #31
    That's for sure. At that freq a screw terminal could look inductive, capacitive or both.

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    • #32
      I have used solder-it paste for years to solder to aluminum chassis while building electronic projects. Really works well. Here is a link to more information.
      http://www.solder-it.com/shop/item.aspx?itemid=89
      And yes, I am a Ham Radio Operator
      George
      My Web Site
      www.mrrace.com
      Builder & Test Pilot N73EX

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      • #33
        Never seen that here but this is a small and isolated town. Looks useful. I will have to see if I can find a distributor that will ship here and that doesn't use UPS.
        Free software for calculating bolt circles and similar: Click Here

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        • #34
          Originally posted by Evan
          One of the problems of using a strictly mechanical connection is due to the dimensional constraints when dealing with gigahertz frequencies. There isn't room for a reliable physical connector that won't disturb the electrical properties of the antenna. The spacing of the elements, the dimensions of all parts and the connections to the driven element are all critical. For instance, to achieve close to the theoretical maximum gain the lengths of the antenna elements must be correct to within a tolerance of about +- .007".

          Building such an antenna array isn't just a matter of bending up some wire. It actually becomes a machining exercise.

          As for corrosion of the joints and the rest of the antenna it will be sprayed with clear lacquer for protection. I will post pictures of the antenna when I have something .
          While on this topic does anybody have a suitable downconverter lying around that will work with a Yaesu FRG 7700 that they don't need and would like to trade?

          The antennas are designed for the 1296 mhz amateur band.
          But Evan, we all know that, in the final analysis, your precision antenna will work well only after you start hanging pieces of aluminum foil on it !

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          • #35
            And don't forget to wrap up your smart meter in aluminum foil before firing up the receiver
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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            • #36
              The smart meter is being dealt with. I am in discussions with BC Hydro right now over the potential interference problem. They don't know what to do. Nobody has complained that Hydro's meters will interfere with their radio telescope before. I am suggesting they do the same for me as they will certainly be doing for the Dominion Radio Astrophysical Observatory in Penticton, which will be a wired smart meter or even the old style. After all, I am a long time member of the Royal Astronomical Society of Canada and will be doing the same type of research. In the past I have contributed earthquake data from my seismograph to the Pacific Geoscience Centre. Amateur astronomers routinely contribute data to the professional astronomers.

              Interference is a high probability since I also intend to build a wide band helical array to cover from about 800 mhz to 1200 mhz with a wideband noise receiver. We are in a radio hole here with very little interference in that range. If they don't make any accommodation then I will be building a stylish little shielded box for it with a screen door than can be closed when necessary. If they don't like that they can go suck eggs. They don't have a legal leg to stand on since the meters are not permitted to interfere with anything. If necessary I will get my amateur ticket which will give me legal priority to them on the 902 to 928 ISM band since Ham radio is a secondary licensed user of that band and they are unlicensed.
              Free software for calculating bolt circles and similar: Click Here

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              • #37
                But Evan, we all know that, in the final analysis, your precision antenna will work well only after you start hanging pieces of aluminum foil on it !
                Precision is relative. +-.007 isn't a very demanding tolerance.
                Free software for calculating bolt circles and similar: Click Here

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                • #38
                  Try this link. Ed


                  http://www.muggyweld.com/1clip7.html

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                  • #39
                    What I dislike about that and the Solder-it products is that they both rely on very active fluxes with the potential to produce corrosion after the join. This method I am using doesn't use any flux other than that found in regular radio solder.

                    It does look worthwhile for joining aluminum to aluminum for small projects.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #40
                      OT for Evan

                      Evan, you are "wise in the ways of science.....";

                      What is your take on the Lightsquared/GPS spectrum controversy?

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                      • #41
                        I really don't have an opinion on that particular issue. It's a clearly definable problem in technical terms, the rest is all politics. Spectrum is worth an incredible amount of money and they aren't making any more of it. Any time there are trainloads of cash involved science issues tend to become a victim of war along with truth.

                        How much trouble will it cause, if any? That depends on who you ask and who pays their salary.

                        The smart meter issues are the same even if you leave out the lunatic fringe. The law says that part 15 devices must not cause interference (part 210 in Canada, same rules). The problem with that is that anything that transmits will cause interference to something sometimes. So now you have an absolute legal paradox and that immediately throws the problem into the political arena since it is politicians that make the laws.

                        There are some very interesting aspects to the smart meter and smart grid program. One in particular is the absolute insistence on the part of the power companies that the system must be real time and bidirectional to to work. The companies have wrapped themselves in green cloaks claiming that the smart grid will save the world by reducing energy consumption.

                        Even if you buy that line it is easy to demonstrate that a smart grid doesn't require real time bidirectional communications to the household level to function. All the meters require is the ability to receive commands in real time and that can be easily provided on numerous existing parts of the spectrum from ground FM radio sideband signals to direct satellite radio. Return data on consumption can be stored in the meter and sent by many possible means on a monthly basis.

                        The decisions to change daily and hourly operating parameters on the grid in order to save energy will never be made based on the information provided by a single user. It will be based on overall energy use and availability in entire regions which the system operators already have. That information is available minute by minute.

                        So why the insistence on having the meters all connected in a high speed IPv6 network?

                        It doesn't take much imagination once it is pointed out to see where that leads. The power companies want to become information service providers. Once the smart meter system is in place it is tiny extra step to start selling you internet, telephone and related data services. The meters are even equipped to interface to your home wireless network directly.

                        Supplying you not just with electric power but all your communications needs is worth an enormous amount of money. And that is the rest of the story.
                        Free software for calculating bolt circles and similar: Click Here

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                        • #42
                          Beware of liquid solder flux. For many years, when I've needed additional rosin flux, more than what's held in cored electronics solder, I've used solder paste. It just more of what's in cored solder, which I've never found to be conductive. Then one day, while designing a one off microcontroller board I grabbed some clear liquid flux that my customer had in their Bio-Med shop. When I did a test run the ADC input/output wasn't working anything like it did on the protoboard. I examined all of my joints under magnification and everything looked looked good. So what was the problem?

                          I took some voltage drop readings across my resistive divider on the ADC input and they were all wrong! I then took some Ohmmeter readings, with the power off, and they were all messed up too!

                          I then stuck the probes in the container of liquid flux and eek a half inch gap read <10K! The board required more than 4 thorough solvent scrubbing's, with a tooth brush, to get this stuff off. All worked fine afterwards though.

                          FYI: For those that will say that I should have defluxed it from the get-go... I usually do that operation after the basic I/O testing.

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                          • #43
                            Originally posted by Evan
                            Spectrum is worth an incredible amount of money and they aren't making any more of it.
                            That's why the Amateur Radio motto has been "Use it or lose it.", ever since the loss of the 11 meter band to CB.

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                            • #44
                              Muggyweld

                              Don't know if the flux would be an issue, but this stuff has been around for awhile and can be a lifesaver at times.....It's quite pricey, and I don't know if an alternative to UPS is available.....

                              http://www.muggyweld.com/index2.html

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                              • #45
                                I then stuck the probes in the container of liquid flux and eek a half inch gap read <10K! The board required more than 4 thorough solvent scrubbing's, with a tooth brush, to get this stuff off. All worked fine afterwards though.

                                That was a lesson I gained way back. I had several jobs in succession in electronics after I dropped out of Berkeley. One was at a company that built radiation detectors of all kinds. They hired me in quality control. They had one model that was used for detecting alpha by means of ionization in an atmospheric air chamber with an ultra thin conductive rubber membrane cover and a detector grid. The detection circuit input stage was a differential amp that used the then very latest in transistors, a dual mosfet. Because of the extremely high input impedance it was imperative that the chamber and all insulation for the detector grid supports be cleaner than Mr. Clean. Even a finger print would cause problems.

                                They were having problems with leakage and erratic operation of the finished units and nobody other than the long gone original engineer who designed it knew anything about mosfets. I developed a washing protocol for the detector chamber after assembly that required a three stage wash in an ultrasonic bath using acetone, distilled water and anhydrous ethanol to remove every trace of conductive contamination. That solved the problem completely.
                                Free software for calculating bolt circles and similar: Click Here

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