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#1
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Does anyone know where I can find Er tables for various type and diameter
of metal tubing so I can calculate Velocity coefficient Vp ? Thanks in advance Regards David |
#2
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![]() "David" wrote Does anyone know where I can find Er tables for various type and diameter of metal tubing so I can calculate Velocity coefficient Vp ? ===================================== The velocity factor of any conductor, including tubes, depends only on what surrounds it. If the surroundings are air, which is mainly oxygen and nitrogen, then the VF = 1.00, equivalent, in metric units, to a velocity of 300 metres per micro-second. Or in ancient, old-fashioned units, it is the far-less-convenient 669600000 miles per hour, give or take a few 100,000 miles. Who cares? --- Reg. |
#3
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OK, so the electrical wavelength of the tube will only be effected by
the dielectric material and it does not make any difference how large the gap is between the Sleeve and the Coax ? The frequency of operation is 920 MHz. Do you happen to know what the covering is made of on the outer sheath of RG174 ? The cable I have has a stranded inner core and seems to have a PFTE dielectric. (Doesn't melt at all when soldering so I assume this is what it is). Reg Edwards wrote: "David" wrote Does anyone know where I can find Er tables for various type and diameter of metal tubing so I can calculate Velocity coefficient Vp ? ===================================== The velocity factor of any conductor, including tubes, depends only on what surrounds it. If the surroundings are air, which is mainly oxygen and nitrogen, then the VF = 1.00, equivalent, in metric units, to a velocity of 300 metres per micro-second. Or in ancient, old-fashioned units, it is the far-less-convenient 669600000 miles per hour, give or take a few 100,000 miles. Who cares? --- Reg. |
#4
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what sleeve and what coax? you asked about Er for tubing and didn't mention
any other components. "David" wrote in message ... OK, so the electrical wavelength of the tube will only be effected by the dielectric material and it does not make any difference how large the gap is between the Sleeve and the Coax ? The frequency of operation is 920 MHz. Do you happen to know what the covering is made of on the outer sheath of RG174 ? The cable I have has a stranded inner core and seems to have a PFTE dielectric. (Doesn't melt at all when soldering so I assume this is what it is). Reg Edwards wrote: "David" wrote Does anyone know where I can find Er tables for various type and diameter of metal tubing so I can calculate Velocity coefficient Vp ? ===================================== The velocity factor of any conductor, including tubes, depends only on what surrounds it. If the surroundings are air, which is mainly oxygen and nitrogen, then the VF = 1.00, equivalent, in metric units, to a velocity of 300 metres per micro-second. Or in ancient, old-fashioned units, it is the far-less-convenient 669600000 miles per hour, give or take a few 100,000 miles. Who cares? --- Reg. |
#5
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![]() "David" wrote in message ... OK, so the electrical wavelength of the tube will only be effected by the dielectric material and it does not make any difference how large the gap is between the Sleeve and the Coax ? The frequency of operation is 920 MHz. Do you happen to know what the covering is made of on the outer sheath of RG174 ? ======================================= The jacket of coaxial cable is usually a soft grade of poly-vynil-chloride, PVC, which can have a dielectric constant anywhere between 4 and 6. The velocity factor along the outside of the coaxial braid depends on the thickness of the jacket. To make much difference to the VF it has to be an inch thick or more whereas it is probably only about 0.6mm. I will have a guess and say the VF is about 0.95. You can forget about it. ---- Reg. |
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