| Author |
Message |
    
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 233
Registered: 7-2004
| | Posted on Sunday, August 22, 2004 - 8:44 pm: | 
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I think I have this right but would appreciate an expert opinion.
The antenna should be at least 36 feet off the ground to the feed point. There should be no metal objects within 18' of the feedpoint. There can be metal objects within 18' below but not at or above the feed point of the antenna.
I would like to have the I-Max 2000 at 36 feet to the feedpoint, but it's at 30' on a tri-pod. Is it going to be noticable after having it at just over 36 feet?
I had to move the antenna because it was in a tree and the base was banging against a heavey branch even in light wind. |
Bc910
Member
Username: Bc910
Post Number: 71
Registered: 7-2004
| | Posted on Sunday, August 22, 2004 - 10:05 pm: |
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In my experience all those rules are great, and in a perfect world we would all abide by them, but This is not a perfect world,
Sometimes you can’t go as high as you like because of an obstruction
Sometimes you can't get the antenna you want because your wife says its ugly, bla, bla, bla
Just do the best you can and it will work out. I think I only followed all of those rules once and only for a short time, why? Because it's hard, simply put.
BC
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Bob_p
Intermediate Member
Username: Bob_p
Post Number: 234
Registered: 7-2004
| | Posted on Sunday, August 22, 2004 - 11:13 pm: |
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Bc910 thanks for the input, and I know what your sayinig. I just want to see if there's going to be a real difference between the two hiegths. One thing tht was strange was the SWR went up when I moved it away from the tree. But like you said it do your best and it will work out. |
Tech548
Moderator
Username: Tech548
Post Number: 254
Registered: 5-2004
| | Posted on Monday, August 23, 2004 - 3:34 am: |
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Bob
A couple of feet one way or the other won't really make a noticable difference. Now if you were to go up yet another 36 feet, then yes, your antenna would see a farther horizon...the same as YOU would if you were up that high.
Simple guidline to go with....the higher the antenna is mounted, the farther away it will reach out and be heard.
Jeff
Tech548 |
Bc910
Member
Username: Bc910
Post Number: 77
Registered: 7-2004
| | Posted on Monday, August 23, 2004 - 10:33 am: |
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With my experiance, that is true Jeff, but correct me if I am wrong. It seems that when someone goes realy high they start to lose a little bit of local strength. They can still be heard but no more "spanking needles"  That's what has happend to me any way. As far as the height goes 30-36 wont make a whole lot of difference, no, your right.
BC |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 235
Registered: 7-2004
| | Posted on Monday, August 23, 2004 - 12:47 pm: |
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Thanks Jeff what do you think of putting a 2 meter antenna about 10 feet from the I-Max. It wouldn't be as high but I would like it to get up about ten feet above the feedpoint?
Thanks again
Bob |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 238
Registered: 7-2004
| | Posted on Monday, August 23, 2004 - 4:58 pm: |
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I was afraid to put the 2 meter above the feedpoint of the I-Max that's 10-13 feet away.
I have a neighbor who said he would put the I-Max on the top of a Lodge Pole pine about 100 foot tall, but with the way the tree swings in the wind I have to wonder how safe it would be.
My wife would kill me if I bought a tower, but I could get some guide wires and put them on the mast pipe and get maybe another 10 feet from what I was told. By the way I was told that 10 foot of free standing mast pipe in a tri-pod without guide wires would be ok, but any higher and you need the wires. Would the extra 10 feet be worth the effort?
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Bob,
Personally I would not put it in the tree. Your antenna would sway way too easily and way too much. Doing this is very hard on the structure of the antenna.
And as far as the "extra 10ft" that you mentioned, any heigth increase is always a bit of a plus but you have to remember, the higher you go with your antenna, the more prone you are to lightning strikes.
The I-Max 2K and the A-99 are capacitance grounded antennas and any lightning strike to them will shred fiberglass them all over your lawn whether your tower is grounded or not.
Jeff
Tech548 |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 247
Registered: 7-2004
| | Posted on Tuesday, August 24, 2004 - 1:20 am: |
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Well I'm on the upslope of an east facing mountain. I have about 1000 feet above the valley floor and no mountains on the other side of the valley that block my signal to east or south with a pretty good shoot north too. Not quite as good because about 10 miles north there is a mountain range that is at about 10000 feet or about 2700 feet above my location. On the other hand I have the west blocked by the upslope I was talking about. It tops out at wewll over 11000 feet. |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 248
Registered: 7-2004
| | Posted on Tuesday, August 24, 2004 - 12:22 pm: |
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I guess I might be a little higher than I thought from the valley floor.
http://www.bigbear.com/updates/cams/sscams/
the web-cams above are placed at or very near my altitude. So if the valley is at 7000 feet I would say I was closer to 7800 feet. Just a guess but near that. The Terrain Park cameras are pointing east and the KNBC Slope Cam is point north east of me. You can see a mountain range over pn the far side. I live about 4 miles south of where the cameras are and the mountains are clear to the east and south of me, and you can see what I was saying about to the north. But again to the west I am blocked by Sugarloaf Mountain |
