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KJ7U SWR experiments
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Frequency
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Configuration
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A
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B
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C
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D
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E
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F
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1.8-2.0
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no tune
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no tune
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no tune
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3.5
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no tune
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4.3
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1.3
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3.6
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no tune
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4.3
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1.4
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3.7
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no tune
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4.1
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1.3
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3.8
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no tune
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4.1
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1.4
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3.9
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no tune
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4.0
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1.1
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4.0
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no tune
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3.9
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1.1
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7.0
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2.8
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2.7
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1.1
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7.3
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2.9
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2.8
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1.4
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10.125
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3.0
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3.1
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1.2
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14
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4.0
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3.9
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1.5
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14.4
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3.8
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3.8
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1.4
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18.11
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4.2
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3.4
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1.4
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21.2
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3.8
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3.0
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1.5
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24.9
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3.0
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2.9
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1.0
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28.0
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4.5
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3.9
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1.3
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29.7
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1.8
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3.7
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1.1
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50
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1.9
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1.5
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1.8
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52
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2.0
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1.3
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1.8
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54
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2.1
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1.4
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1.8
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Configuration A: Clearly something is wrong here! As this was my first test of the unit, it was disappointing, but
usually something this bad, indicates an installation problem
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Configuration B: I was using a piece of PVC white pipe as an insulator between the antenna and the mount: BAD IDEA!!! It
seems this thing is almost a conductor at HF, I took this out and had stood without the top mount (air as an insulator) This is actually the fourth test: so it had the bottom coil disconnected as well Well I have
80M tuning, but the SWR is still higher than I would like: what is the problem.
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Configuration C: Even though I had not touched the grounding system after testing the HS1800, I thought it might be a
problem for this antenna, so I added an extra strap between the mount and the truck body. WOW!!! Big change! Is it that the antenna is more sensitive to grounding or is it that one of my grounds broke? I dont know..
in anycase this is pretty nice operation. (Ran this configuration with a Top hat for about 2 months)
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Still to do: I want to test the effect of the coil at the base of the antenna.. so I left some columns in the table: stay
tuned!
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Copyright 2004 by Philip P. Thompson, All rights reserved.
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