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Author Topic: tin roof hf vertical?  (Read 792 times)
KF7MW
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Posts: 3




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« on: March 08, 2010, 07:51:15 AM »

I am reassembling some stations after years of quiet.  One of my shacks will be a 12ft tall 25x40ft steel building.  Roof slopes at about 20degrees. I have a TS440 i'll put out there.

Suggestions for skyhook?

I could for example mount some sort of vertical from the center of the bldg and add a few radials as necessary.  I'd like to do 40m/15 but other bands would be a bonus.  Intuitively, this seems like a good solution.  Experience has shown I have an uncanny knack at building intuitive things that yield hi swr :=)

Alternatively, I have about 40 ft of that mil surplus fiberglass mast that would look real nice sticking out from the center of the roof with say an inverted v for 40.  Would I be too near the metal roof to do that?  I have lots of trees around and could use them to do a flat dipole as well.

Suggestions?  Guess I'm thinking I should somehow try to leverage that bunch of steel.
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KE7YDY
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Posts: 38




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« Reply #1 on: March 08, 2010, 10:11:44 AM »

Shot my dipole is only about 15ft above a tin roof and I talk just fine with low swr. Besides as long as you don't fry the radio and the antenna talks who cares what the swr is. I have talked on a 15 ft dipole on 40m and still got out fine. good lick and enjoy.
KE7YDY
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KC5CQW
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Posts: 98




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« Reply #2 on: March 08, 2010, 10:15:51 AM »

33' of the pole to make a 40/15 vertical sounds good to me.
You may need an SGC tuner at the feed point.
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KC5CQW
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Posts: 98




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« Reply #3 on: March 08, 2010, 10:21:34 AM »

Use only 22' for lower radiation angle on the upper bands if you chase DX. You will definitely need a single ended tuner at the feed point here.
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KQ6Q
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Posts: 973




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« Reply #4 on: March 08, 2010, 12:30:50 PM »

To keep from making the roof leaky, avoid making any holes in it. Consider putting up a mast with the top level with the roof, on a side or corner opposite the direction you'd like to favor, and put a trap vertical on that mast, with the ground side bonded to the metal roof. if you need more coverage in other directions, some tuned radials outward in those directions can help. or put up two masts, one at either end of the peak of the roof, both with the ground side bonded to the roof, and either have a coax switch to feed either mast separately, or if you can wild and crazy, set up a phasing system to be able to steer the array.

Fred, KQ6Q
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WX7G
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Posts: 5985




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« Reply #5 on: March 08, 2010, 08:21:03 PM »

The inverted-vee is the plug and play solution. It will work quite well.

A vertical on the roof should work well too but will need some tuning. I recommend the Hustler 4BTV. Only $124 from DX Engineering. You might have to adjust the traps per the 'good ground' tuning method they have posted. For this you really want to have an antenna analyzer such as the MFJ-259B.
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