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Author Topic: 300 ohm vs 450 ohm ladder line length for a G5RV  (Read 6005 times)
KT0DD
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Posts: 410




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« on: July 05, 2012, 03:27:54 PM »

Is there a difference in the matching stub length on a G5RV if you use 450 ohm ladder line vs. 300 ohm twin lead? What would be the optimum length of 450 ohm ladder line on a G5RV. Thanks all. Todd - KT0DD
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WB6BYU
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Posts: 17270




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« Reply #1 on: July 05, 2012, 03:59:30 PM »

The line impedance affects the SWR on each band.  The velocity factor (which varies
depending on how the line is built) affects the optimum length of the matching section.

Lots of good information here:

http://www.cebik.com/content/a10/wire/g5rv.html
http://www.vk1od.net/antenna/G5RV/index.htm
http://www.vk1od.net/antenna/G5RV/optimising.htm
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W5DXP
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« Reply #2 on: July 06, 2012, 07:25:06 PM »

A G5RV works better with 300 ohm feedline than with 450 ohm feedline because 300 ohm twinlead does a better job of transforming G5RV feedpoint impedances closer to 50 ohms.
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W0BTU
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« Reply #3 on: July 07, 2012, 08:24:38 AM »

There are alternatives to the G5RV, depending on what bands you want to operate. See http://www.w0btu.com/g5rv_antenna.html
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