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Author Topic: ATAS 120 Hi Swr  (Read 366 times)
DAVIDRITAH
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Posts: 2




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« on: February 26, 2005, 03:32:25 PM »

Have this antenna mounted for about a year on a 40' diesel pusher motor home, on the top of the ladder. worked diligently to insure good grounding to the ladder + pulled # 12 insulated doen thru the ladder vertical sections to the chassis. Worked like something out of star wars...swr excellect and used it on 20 only. Could't beleive it. Went to use it today and the swr is sky hi. Using it on an MK11G with MJP manual controller. Cleaned all the grounds to shiny & bright but swr is still Has anyone any thoughts. Motor runs fine....unit goes up & down. has any one taken one apart, if so ...your thoughts and...how do u disassemble with out destroying it. Thanks in advance for your time
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K0BG
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« Reply #1 on: February 26, 2005, 05:10:15 PM »

I'm surprised it worked at all. The ladder you mounted it on may indeed be DC grounded. However, vertical antennas require a groundplane which is essentially the "other" half of the antenna. Quite obviously, the ladder is a poor groundplane. The original SWR was low for two reasons. One, the antenna is rather lossy, and two the lack of a good groundplane.

Now that the SWR is too high and can't be brought down to an acceptable level indicates another problem altogether. I suspect that one of more connectors loose or have water in them. Perhaps even the antenna has water in it.

The first thing to do is replace the antenna with a dummy load and recheck the SWR. If it isn't okay, you have a problem with the coax. If it is okay, then start looking at the antenna. Whether or not it is DC grounded makes little difference in this case.

Alan, KØBG
www.k0bg.com
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DAVIDRITAH
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« Reply #2 on: February 26, 2005, 08:25:25 PM »

Thank you for taking the time to answer my memo. Much appreciated and will proceed to look into your comments and suggestions.
Once again, 73 & Thanks
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