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Coax ![]() |
1/4 Wave bamboo-3 ![]() |
80m ![]() |
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2020 |
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Velocity |
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Transformer Transmission lines a half wave in length come full circle by mirroring the impedance on one end to the other. An open circuit at one end will appear as open at the other. A short at one end will appear as a short at the other. Note in both figures above the distance a wave travels is shortened by the dielectric properties of the coaxial line. This fact is represented in transmission line characteristics as a variable called Velocity Factor… a unit-less number indicating the fractional speed of light in transmission lines with respect to the free-space speed of light. (Copyright) kx4o@ www.hamradio.me |
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Capacitance Checking the calcultated and measured capacitance. Both are ~52pF/m. The physical length of a line section is not the same as its electrical length, and they are related by the Velocity Factor (VF) where VF=PhysicalLength/ElectricalLength. The most straight forward method of calculating the electrical length of a piece of coax involves first calculating the free space wavelength of the target frequency and multiplying by the velocity factor of the coax. For COAX-3 the velocity is 85%: cutting 1m
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Quarter wave Because this cable is not UV-resistant, I decided to supply a PE water tube around it. Using silicone spray en a lot of forece, finally it worked.... |
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7/16 adjusting These connectors are to small and therefore using the lathe for drilling them up. |
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Installation 1![]() Cutting the outer shell |
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Installation 2 -Cutting the copper foil with a small tube cutter. -file away sharp edges and insterting the outer ring |
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Installation 3 -thickening of the inner conductor by soldering -fit the plug with a dummy and hit the parts together with a hammer |
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Installation 3 -First apply Scotchfill anf finishing with Scotch tape with sufficient force |
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Measurements minimum resistance = 2,2R @ 3620 KHz |
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