Base Coax and Antenna Setup

[Ckeith11]

I'm getting ready to start a base set up in my shed on the side of my house and have decided on the following equipment.
-IMAX 2000
-Uniden 68 LTW from my mobile (Peaked and tuned)

I have a few questions about the whole setup.

1. I plan on mounting the antenna in the middle of an open area in my backyard next to a 30 foot tree to disguise it somewhat. Now will the tree cause any interference with the antenna?

2. If I am concreting a metal pipe into the ground and attaching my antenna to this, what kind of grounding will I have to do, and will I need a ground plane kit?

3. Will RG-8X coax inside a PVC pipe running to my shed underground last, is it of good quality?

4. Can I use a transformer to a wall socket for power, or should I buy an external power supply? BTW I don't plan on running an amplifier because I am close to I-95.

5. Is there anything else I have to know about antenna setup?

Thanks for taking the time,
-Curt

[drdx]

1. I plan on mounting the antenna in the middle of an open area in my backyard next to a 30 foot tree to disguise it somewhat. Now will the tree cause any interference with the antenna? -I've done the tree deal with great results, but results will vary. Can you simply mount it to the tree, not do the pipe and concrete deal, and run down a ground an coax? 30 foot trees sound like a nice high antenna perch. I used industrial zip ties once on a vertical and had it in a tree for years trouble free. I used the uv resistant ones and checked them frequently. I did find a handy branch aiming upward, not far from the trunk, and cut it off an modified it for my mounting pole to slide on to.

2. If I am concreting a metal pipe into the ground and attaching my antenna to this, what kind of grounding will I have to do, and will I need a ground plane kit? -a ground rod for lightning would be nice, I'd skip the ground plane in your case

3. Will RG-8X coax inside a PVC pipe running to my shed underground last, is it of good quality? I'd use RG213 or LMR400. Use the gray electrical stuff, and where it comes out of the ground, anywhere outside, make the pvc come up and then uturn down, to prevent water entry, and seal the end with silicon or foam.

4. Can I use a transformer to a wall socket for power, or should I buy an external power supply? BTW I don't plan on running an amplifier because I am close to I-95. -use the wall socket if barefoot. Why would being by the highway matter? conversation there will be boring listening to passers by, and if it's not, you'll want the power, but let it wait until you get the antenna and radio ironed out. If it is a healthy circuit, even when you move to an amp, you're good into the 750 watt range or so, depending on other devices on the circuit and the amp being used before concern.

5. Is there anything else I have to know about antenna setup? -height is everything here, and the higher the better to keep out of the neighbors tv's. Watch the modulation and wattage and better yet get yourself a low pass filter to help curb the neighbor interference issue, if you're in a neighborhood

-drdx

[Ckeith11]

Thanks for responding!
In regards to the individual questions......

1: I cant slap it in the tree, and I'm trying to do everything by the book because my neighbor calls code enforcement on everyone, so the tree is a no go due to a code stating no more than 10 foot over the house which I am already pushing by putting in a 25 footer. Will there be any kind of problem with the grounding on the concrete and pipe idea or is there a better way to do it?

4: I do plan on moving to a small amplifier later, but for now I plan on running barefoot.

Also, what would be a good place to ground my antenna on my shed? I'm fairly new to the whole electronics thing.

[80 meter man]

Yes you need a power supply to power your radio. I would go with a supply that gives 20 amps constant. A wall wort will not power any CB radio. They're to small.

I have a tree issue here. I find that the tree does affect radio performance. Keep it away from the tree or mount it to the top of the tree like DRDX said,

For the coax I would use LMR-400DB the DB meaning Direct Burial. I know you will be using PVC but if any water gets in there the DB coax will save you from a lot of problems.

You will need a ground other than the mounting pipe. If you use the mounting pipe as the ground and lightning hits your antenna is most likely will split your concrete base. You should drive an 8 foot coper rod next to the base and connect it to the pipe with coper strap.

Ground plane kit will lower your take off angle. That means your signal will radiate of your antenna in a direction closer to the horizon. This is better for local talk but not as good for skip talking ( I know I might get other opinions on this. Bring them on I would like to hear your ideas on ground planes)

[drdx]

Sounds like you're off to a good start. Good advise in the DB coax. 80 meter man, I'm a ground plane fan, but in his case, I feared extra visual exposure and a lowered angle of radiation causing extra TVI attention. I'm a sloped radial fan, by the way, always in search of that extra .3 db per Mr. ORR, W6SAI is it?? In the past, I made my ground plane kits built into the top set of guy wires. -drdx

[80 meter man]

Sounds like you're off to a good start. Good advise in the DB coax. 80 meter man, I'm a ground plane fan, but in his case, I feared extra visual exposure and a lowered angle of radiation causing extra TVI attention. I'm a sloped radial fan, by the way, always in search of that extra .3 db per Mr. ORR, W6SAI is it?? In the past, I made my ground plane kits built into the top set of guy wires. -drdx

Any fan of Orr is a friend of mine. I love his books. Some people call him the west coast ARRL. I like ground planes also but I don't have one on my Imax!! I need to get it down and put a kit on it or open the wallet and get the Maco I'm putting up some new antennas this week i will post a photo when done. It's a 27 foot guyed mast with 3 antennas on it. I like your guy wire ground plane idea. How did it work for you? What length did you use for 11m?

[drdx]

I use 234 divided by my target frequency, but if you're guying a mast in more than one place, you have a real opportunity. You can put a 2nd set of radials, same length, etc. 1/4 or 1/2 wavelenght down the mast, whichever the case may work out, below for added benefit. I can't remember where I read it, maybe in an orr deal or an arrl deal, but it was before the internet. Try to maintain the same angle on the top and bottom set and of course space them around as symmetrical as possible. In other words, you'd have your guy wire/ground plane radials at the base, then below another set. The radial length is not that sensitive but I can tell you I tested 2 antrons, 30 feet apart, one with my guy radial kit (4 radials) and one without, and on local signals, there was a needle width benefit with the radial antenna, and it was 10 foot lower. That is a lot in the big picture. -drdx

[Ckeith11]

Thanks for the replies guys. What kind of wind will the IMAX hold up in?

[linx]

Thanks for the replies guys. What kind of wind will the IMAX hold up in?

Hehe, I had my Imax 50 ft on my tower, and that thing would almost bend in half in a thunder/wind storm. If the wind go up to 60 mph or so, it looked rough, but she would hold it out. I don't think you have any problems with it breaking in wind. I now have it mounted on a 15 ft piece of pipe in the back yard, and it almost gets out as good as it did on the tower.

I do have the GPK on my Imax. Does it do anything? I don't think so. I am a fan of Ground Plains on other antennas like the Penetrator or the Maco 5/8, but I'm just no convienced it does anything other than shoot the single over to my neighbor's tv. Plus, my Imax is 1-1.5 years old, and the "chome" braket the GPK radials mount to is a rust bucket.

I think you'll have a good little setup there. It's hard to beat an Imax, and I'm a fan of running mobiles in the house/shop.

How tall is the pipe you are concreting into the ground? What gauge is the pipe? I am concerned about having guy wires, and concerned about lifting a really tall, heavy wall pipe. It took 3 of us big guys to lift my 15 ft pipe and put it in the corner post of my chain link fence.

[Ckeith11]

I don't know what gauge pipe I'm going to use, but I'm only going to have 3-4 feet sticking out of the ground. The pipe is only serving as a mounting bracket.

[TwentyTwo-Zero]

I don't know what gauge pipe I'm going to use, but I'm only going to have 3-4 feet sticking out of the ground. The pipe is only serving as a mounting bracket.

Having the antenna mounted 3-4 feet off the ground will severely effect the radiation pattern and the antenna will be less efficient. Also, chances are pretty good that you will be "bouncing" your signal right into your neighbor's houses which (more likely then not) will create a "bleed" situation. They won't need to "see" your antenna to know you have a radio - they will "hear" you - especially if they have poorly filtered equipment (phones, pc speakers, etc.). Ideally, you want to have your antenna mounted 36 feet in the air at a minimum. This will do two things for you - 1) It will (hopefully) place your "take off angle" (angle of radiation) above the roof line of your neighbors which will decrease the possibility of "bleeding" on them. 2) More importantly - it will place your antenna 1 wavelength off the ground and allow it to perform more efficiently in the (11m) band it was designed for. I understand you wanting to "hide" the antenna from your neighbors, but placing it that low to the ground (IMHO) will create the exact problems that you are trying to avoid. Good luck...

[Ckeith11]

OK I'm putting the antenna on top of a 6 foot pole, but that's the best I can do due to the strict codes in my area. Will the 5 feet I'm missing affect me a terrible amount? I'm not looking to reach halfway around the world or anything, I just need something I can talk a reasonable distance with.