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#1
August 19th 07, 10:01 PM
posted to rec.radio.amateur.antenna
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How much can the impedance of coax vary from its characteristic impedance?
I bought some no name RG-59/U coax (RG-59/U-SP-95 Made in the USA). I
went to cut and tune a 1/4WL matching section for 3.8Mhz. I cut the coax a little longer because I intended to tune it with my MFJ259B or.LP100 exactly to the design frequency. I have a 50 Ohm dummyload that actually is about 54 Ohms @ 3.8Mhz. Plugging the numbers into ON4UN's program for calculating impedance along a coax line: Given the coax is 75 Ohms and the load is 54 Ohms, the program reported that if the line was a 1/4WL long the impedance at the source end would be about 105+j0 Ohms. How long is the coax (in feet)? Are you sure you didn't actually cut a half wavelength? Tor N4OGW |
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#2
August 19th 07, 10:07 PM
posted to rec.radio.amateur.antenna
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How much can the impedance of coax vary from its characteristic impedance?
How long is the coax (in feet)? Are you sure you didn't actually cut a half wavelength? Which wouldn't make sense either, then you should get 54 ohms. Tor N4OGW |
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