G5RV & Very High SWR
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| Jan 2nd 2016, 00:26 | |
AI6OZJoined: Nov 7th 2003, 10:54Total Topics: 0 Total Posts: 0 |
I have recently purchased a G5RV Mini Band antenna that covers 20, 17, 15, and 10 meters. My home station consists of FT-950, MFJ-929 tuner, LMR-400 low lost coax line all connected to my G5RV antenna. The G5RV center mounting bracket is currently mounted on 10 foot PVC pipe about 25 feet above ground. The PVC pipe is in turn mounted on a metal pipe (giving me the 25 feet above ground) and there is about 8 feet between the metal pipe and the G5RV center mounting bracket on the PVC pipe. The G5RV copper stranded wire is mounted similar to the G5RV center mounting bracket along the edge of my garage giving it a L – shape configuration, also about 25 feet above around. The area around the G5RV consist of the two garages the antenna is mounted between, one large RV parked in front of my neighbor’s garage, and the utilities power and phone about 10 feet or so behind/next to the antenna. My problem - The 20, 17, and 15 meters bands all have very high SWR and the MFJ-929 tuner is unable to adjust from the very high SWR down to a low SWR. 10 meters has no difficulties tuning to a low SWR. I have a LMR-400 coax 6 coil choke inline (or not inline) but this doesn’t seem to make any difference, I still get very high SWR. What I do not understand is why and what I can do about it. Does anyone have any suggestions about why I have Very High SWR and what I can do about it??? Thanks |
| Jan 2nd 2016, 00:47 | |
W1VTSuper Moderator Joined: Apr 4th 1998, 00:00Total Topics: 0 Total Posts: 0 |
http://forums.qrz.com/index.php?threads/making-a-g5rv-mini.349782/ This discussion on QRZ.com suggests that the normal version can be made to work on 10 and 20 meters with a moderate SWR. Bending typically raises the resonant frequency, so you may need to add some wire to bring the resonant frequency back down. http://www.arrl.org/files/file/Technology/tis/info/pdf/9501046.pdf Getting the Most Out of Your T-Network Antenna Tuner QST January 1995, pp. 44-47 Here's how to adjust this popular tuning circuit so it transfers maximum power to your antenna. Zack Lau W1VT ARRL Senior Lab Engineer |
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