| Author |
Message |
    
Chad
Junior Member
Username: Chad
Post Number: 17
Registered: 11-2004
| | Posted on Friday, November 19, 2004 - 12:11 pm: | 
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Hello Al,
I just ordered an Imax 2000, I'm going from a dipole strung in the trees, I cannot wait for a real antenna.
I have a couple questions about mounting, Is it possible to mount the antenna to the peak of a home directly or do I need a grounded mast?
It's late November and we have just had a bunch of rain, I am a little reluctant to dig a hole now and pour concrete as the ground is unstable at this time due to the eminent freeze soon and the ground moisture.
Does anyone know the wind drag of this baby?
When going to a tower will a large pipe work or will I need a 3 leg tower?
The peak of the house is about 25' off the ground. I also have a BIG personal problem with heights. If I could use a pipe I was going to weld up a break system that will allow me to swing the antenna down for service and tuning. Has anyone done this?
Or.... What's the easiest, best looking way to mount an omni that will still perform? Gotta keep the home asthetics (lady) in mind.
Thanks for your input,
Chad |
Highlander
Advanced Member
Username: Highlander
Post Number: 684
Registered: 12-2001
| | Posted on Friday, November 19, 2004 - 5:16 pm: |
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I've mounted them on the roof with tripods, and with chimney mounts. You can use 10 or 15 feet of heavy-duty mast. You shouldn't have any problems with wind load, the antenna is very flexible, and fairly lightweight. It would be a very good idea to run a ground cable from the mast to a ground rod, but the antenna will work fine without one--it is for safety, not the antenna. How steep is the pitch of your roof?
I wouldn't worry to much about rigging up a quick way to bring it down-- There is no real "maintenence" to be done to these, get it up and use good coax, you should be set for several years.
I'm off all next week, maybe you could use a hand? I'm pretty worthless with tools and stuff, but sometimes an extra hand makes a big difference. |
Mikefromms
Intermediate Member
Username: Mikefromms
Post Number: 286
Registered: 6-2003
| | Posted on Saturday, November 20, 2004 - 8:19 pm: |
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Just get it as high as you can and ground the mast. Enjoy.
mikefromms |
Chad
Junior Member
Username: Chad
Post Number: 19
Registered: 11-2004
| | Posted on Monday, November 22, 2004 - 10:00 am: |
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Highlander,
Thanks for your generous offer! I purchased a push up pole at Lowes sat. I discovered that the bottom part of the mast fits EXACTLY outside a peice of 2.25" black pipe after de-burring. I cur a hole in a 1'X1' chunck of plate steel and welded a 4' section of pipe in so that 1' sticks up above the flange. leveled out the mast and shoved 3' of pipe into the ground. Keep in mind you can cut the pipe and weld it to the plate but you must drill an air escape hole onto the plate between the pipe sections or it will bounce back up at you when pounding it in. I attached the mast to the side of my wood shed that is about 20' away from the radio room.
For more hardware store engineering (keep in mind I am limited to Lowes and Tractor Supply.) I bought a ground rod and sunk it 18" from where the coax will enter the house. I ran a 6Ga wire ino the radio room and tied it onto a 12 circ ground bar intended for a GE breaker panel.
In my quest to keep mother nature outside the home I wanted to have the coax ground outside, seems that most coax grounds have a male and female connector and I did not want this. Sooooo. I discovered that a 4/0 copper welding cable eyelet fits perfectly over a ground rod. I crimped and soldered this on and wollered the hole out bigger to accept a F-F inline coupler. Feedline grounding complete. Woo-Hoo!
Mast grounding consists of another ground feed running to the plate that attaches to the bottom of the mast. knowing that the sections of the push up can wobble I elected to ground each section. The second section is grounded with a clamp that holds my son's 4' firestik that was ruined in an altercation I had with a tornado in my truck. It is a placebo antenna that he swears improves his range on his FRS radio (he's 4 and into radio!) His "feedline" is the ground for the second section. The third section is grounded off that clamp. These are tied to the plate.
Now I have to order some burial cable today and get the Imax in and I will be cooking with gas (or at least RF) I'll try to post a pic of the ground rod assembly on the pic thread for commentary.
Btw, Highlander, I was trying to get you during the forum but still can't get out with the crummy antenna, BUT in the middle of calling the 4 Yr old got his first contact. He was on his little Motorola FRS shouting CQ DX, CQ DX and raised a fellow that was out hiking with his family, they exchanged flowers and he was elated, The other guy is a fellow CB'er and was amazed that a 4 yr old kid accepted radio over Spongebob. The things that happen when mama goes shopping! |
bluegrass (Unregistered Guest)
Unregistered guest
| | Posted on Monday, November 22, 2004 - 10:46 am: |
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i've got a few questions.first i'm planing to get the i-max ground plane kit for my i-max 99 and i would like to know how well it performs.my other question is how good an antenna is the maco y-quad?i wanted to get a beam for dx'ing but i don't have a lot of space and i can't afford a tower so it will have to be mounted on an aluminum pole.sence the y-quad is only 6ft. long it just might be the right for me but before i buy i want to know how good it is. 73' from bluegrass kcd-40219 louisvile,ky. |
Mikefromms
Intermediate Member
Username: Mikefromms
Post Number: 293
Registered: 6-2003
| | Posted on Wednesday, November 24, 2004 - 6:48 pm: |
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Chad, how much difference could you tell in the dipole and imax? Of course, they would have to be in similar locations. Any big gains?
Mikefromms |
Chad
Junior Member
Username: Chad
Post Number: 28
Registered: 11-2004
| | Posted on Thursday, December 02, 2004 - 12:22 pm: |
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The top of the Imax is at 44' most of the time but I sometimes run it at 54'. The horz dipole was at approx 30' and the top of the vertical was at 30'. Locations between dipole's and the imax were within 15' of each other. Not really a good accurate comparison but here's what I found... When I had both dipoles up the horz was better for skip, whereas the vertical was suprisingly good for short range. Wind came along and took out the tree that held one end of the horz and the entire vert. I went to 1 horz after that. The dipole received just as good as the Imax although I find the Imax to be quieter in the noise arena. Probably due to the improved grounding. So on the receive end I think the dipole is just as good if not better than the Imax.
The difference comes into play on the transmit side. The Imax smokes the dipole, even with the Imax down to 32' it still kicks butt.
When I started this build I was new to the house and wanted something fast, easy, and hidden. I got the urge to have more and purchased the Imax. I am very happy with it. I have re-located the dipole and am using it as a backup antenna.
The Dipole is a tried and true design, many other antenna's are merely a variation or re-invention of the wheel. I highly reccommend playing with them, they are cheap to build and with several and some switching (as others have mentioned) they can become powerfully directional. The money you save on building can be put into expierimenting!
I never tried using a 1:1 balun, have you? This will make the dipole truly balanced and cut down on feedline radiation. If you try this e-mail or post because I would be very intrested to find out the effects.
Good luck!
Chad |
Tech808
Moderator
Username: Tech808
Post Number: 4202
Registered: 8-2002
| | Posted on Thursday, December 02, 2004 - 12:45 pm: |
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Chad,
The IMAX 2000 is 24' tall
So if you have the tip at 44" the Load is only 20' off the ground.
If the tip is at 54' the Load is still only 30' off the ground.
If the Load / Bottom of the IMAX is less than 36' feet off the ground you will find a GP Kit will be of help and Tech833 have mentioned many times.
You will Notice a difference by adding the GP Kit if the load of the IMAX is only 20' off the ground.
Read BOTH of Tech833's article's for further help / advice they can both be found in the Subscriber (Preview) Area of the Forum here:
Subscriber (Preview) » Product Reviews » Imax 2000 Ground Plane Kit Reviewed » Review
and
Subscriber (Preview) » Product Reviews » Imax 2000 Exposed » Review
Hope this helps.
Lon
Tech808
CEF808
N9OSN |
Chad
Junior Member
Username: Chad
Post Number: 29
Registered: 11-2004
| | Posted on Thursday, December 02, 2004 - 12:59 pm: |
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Lon,
I will do the reading. Thanks for the advice! I almost purchased the GPK when I bought the antenna. sheesh it's only a little extra money! I live in a wooded area and the GPK has a diameter of 12' correct? That's a whole lotta tree trimming! It is doing well now, I may add the GPK when it warms a tad outside. I am also investigating other mounting options. Have you decided how you are going to mount yours yet? I like the black pipe idea but I still may just sink a real mast and go for it.
Chad |
Tech808
Moderator
Username: Tech808
Post Number: 4204
Registered: 8-2002
| | Posted on Thursday, December 02, 2004 - 4:41 pm: |
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Chad,
I got VERY LUCKY. 
Homeboy CEF #159 and I were talking Monday night and he mentioned he was moving and had 3 - 10' Sections and a 9' top section of Rohn 25G tower laying on the ground in back of his garage and gave them to me. 
Now when Spring arrives I wil be able to put it up for the IMAX.
Still waiting until someone can stop by to climb my tower to check the SE beam wires out for me.
If they can't be reached or fixed from the tower I will have to wait and try and find a bucket truck when finances allow.
One thing about it is No Antennas sure gives me a lot of time to get caught up on other things and the Copper Forum,
Lon
Tech808
CEF808
N9OSN |
Chad
Junior Member
Username: Chad
Post Number: 31
Registered: 11-2004
| | Posted on Thursday, December 02, 2004 - 9:01 pm: |
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Lon,
Awwww, Comon, The ground isn't frozen yet  It's supposed to be sunny Saturday!
Seriousily that's a great deal! I've been thinking about going for a "country cruise" and find a farmer that will allow me to remove his tower. I'm on a push up till spring (I HOPE) I can bring it down in the wind, just takes proper planning. I would be much happier with something more sturdy. Oh Well, Gotta make due, I have a weird feeling this winter could be rough.
Chad |
