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Author Topic: I hit a deer  (Read 1543 times)
KD0AFK
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Posts: 245




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« on: November 29, 2007, 11:31:44 PM »

I hit a deer the other day. I had a fear that I would do that some day and I got the truck fixed, but the one thing that happened was that the tarheel that I mounted on my front bumper took one for the team. Fortunately I had installed a 2 foot extention tube and it took the damage. I want to remount the antenna but not on the front bumper. I want to mount it where it won't receive damage unless I roll my truck. I was thinking of behind the sleeper right over the frame of my truck. How much performance loss will I experience with the signal going through the body of my truck side panels. I drive a freightliner century class.
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K0BG
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« Reply #1 on: November 30, 2007, 05:54:12 AM »

Probably a lot! It depends on how much capacitive coupling there is between the antenna and the various parts and pieces. As I say in an upcoming article here on eham, it is the mass UNDER the antenna, not along side, that counts.

Alan, KØBG
www.k0bg.com
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KD0AFK
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« Reply #2 on: November 30, 2007, 08:07:38 AM »

Yes,I know it is the metal UNDER the antenna. No offense, but that line is getting a little stale. You have stated that more times than I can count. When I post a question like this, I am taking the metal under the antenna into account.
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WW5AA
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« Reply #3 on: November 30, 2007, 09:19:52 AM »

I for one do not think that Alan has mentioned it enough! Anyone who wants to go mobile should go to his web site before starting. The answer to your question is what Alan said, it will not work very well. You will have all the aluminum from the trailer above the coil and a lot of the whip to say nothing about all the metal in the cab. Good luck.

73, de Lindy
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KD0AFK
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« Reply #4 on: November 30, 2007, 09:56:15 AM »

The reason I say that it is a stale line is that for big trucks RF grounding is a way of life. Our options are VERY limited and to repeat the obvious every time he posts an answer to a big rig mobile question is like someone saying in response to someone else every time they talk; "the sun is hot". 18 wheelers know that it sux to mount an antenna to their truck but hearing it every time they ask a question just gets old. Alan's web site is very good for cars but for trucks it kind of lacks.
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W3LK
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Posts: 5639




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« Reply #5 on: November 30, 2007, 12:05:09 PM »

<< Yes,I know it is the metal UNDER the antenna. No offense, but that line is getting a little stale. You have stated that more times than I can count.>>

Obviously you don't pay any attention to it or think that you know better. The fact that you don't like the answer doesn't repeal the laws of physics.

I believe you went down this exact same road with your original installation questions. Nothing has changed since then.

Mounting the antenna behind the cab is a bad idea, performance wise.

73,

Lon - W3LK
Naugatuck, Connecticut
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KD0AFK
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« Reply #6 on: November 30, 2007, 01:08:56 PM »

Well, looks like I will go back to the mirror mount. Can't afford to screw up an antenna every time I hit a deer. I have only hit one (so far) but once is enough. Maybe I can rig up a counterpois in the future.
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K0BG
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« Reply #7 on: November 30, 2007, 02:59:43 PM »

Good luck. Here's a WAG for you. I'd almost bet money, that performance when mounted on the mirror bracket, will suffer in the neighborhood of 30 dB.

Alan, KØBG
www.k0bg.com
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W3LK
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« Reply #8 on: November 30, 2007, 04:54:13 PM »

Shawn:

I forgot to say that I'm sorry you had the accident. I know from experience what a deer can do to the front end of a vehicle. I'm also sorry about the damage to the antenna. I'm glad, though, that you were not injured.

73,

Lon - W3LK
Naugatuck, Connecticut
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KD0AFK
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« Reply #9 on: November 30, 2007, 05:23:15 PM »

I will bet you a new kenwood TS2000 that My performance will IMPROVE more than 30db when I mount it on my mirror, because right now it is in the back of my sleeper leaning up against a wall next to my bed cause a deer messed it up. I will also bet you that if I mount it  where the gain is the best and another deer jumps out in front of me the gain will decrease to 0db.
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W3LK
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« Reply #10 on: November 30, 2007, 08:24:41 PM »

<< I will also bet you that if I mount it where the gain is the best and another deer jumps out in front of me the gain will decrease to 0db.>>

You go places where the deer can jump over the top of the cab? <gg>

73,

Lon - W3LK
Naugatuck, Connecticut
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KD0AFK
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Posts: 245




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« Reply #11 on: November 30, 2007, 08:28:06 PM »

No, I go places where deer can jump in front of me. Are you saying the best place to mount my antenna is on top of the cab?
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AA4PB
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« Reply #12 on: December 01, 2007, 03:39:48 PM »

If you mount it on the mirror it will very likely get damaged if you roll the truck. The safest place for the antenna is to leave it at home - but the mobile performance will be rotten :-) If you've only hit one deer in all the time you've been driving then I wouldn't worry about the antenna too much. I'd mount it where it works best. Otherwise, put it on the mirror and accept whatever performance you get.
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W3LK
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« Reply #13 on: December 01, 2007, 04:01:39 PM »

<< Are you saying the best place to mount my antenna is on top of the cab?>>

Yes, that is the best place, performance-wise, but it isn't practical on a big rig. You'll exceed height restrictions and rip it off on some overhead obstruction before you've gone 50 miles.

In the middle of the largest mass of metal is always the best location for an antenna. whether HF, VHF or UHF. All other locations are a compromise. Smiley

73,

Lon - W3LK
Naugatuck, Connecticut
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N6JRZ
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« Reply #14 on: December 05, 2007, 05:08:08 PM »

I agree, Alans site is the best source for info, but I also agree with AFK, its catered more toward cars and pick-ups. I have an SUV and antenna mounting options are very limited especally if you want to use a screwdriver type antenna (ie HS1800DX). I can not find any other place to mount this type of antenna except for the trailer hitch. Alan says this not the ideal place to mount it but no other options are avaiable on an SUV. So I've decided to get and HMC-6S from Comet. I have more options on mounting w/o having to drill a hole in the roof. The XYL would kill me if I did that  HIHI.
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