mobile on top of a mast for base

[longhaireddwb]

I was wanting to come up with an antenna to put at the top of my 40 ft mast. I'm afraid of getting an antenna that is 20 ft. long to put on top of the mast because I live in an apartment. I'm going to put up the mast but with an antenna with ground radials sticking out is really going to be seen!

I'm going to be putting a 2m/70cm antenna that is 10FT. long about half way up this mast on a horizontal bar. I know, this will be easy to see also but on the side of the building I'm putting the mast on it wont be seen by many. But with a 20 ft antenna on top of the mast it will be seen from everywhere! I want to put the 11 meter antenna on the top of the mast so I was thinking of the 102 whip. I also have a pereditor 10-k competition antenna laying around that I could put on the top of the mast.
The mast is steal so I was hoping it would work as the ground plane. I was going to put a ground rod into the ground and connect the ground rod and steal mast together with some kind of ground strap.

These are just ideas. please feel free to give me your opinions on this. I need help with this. I'm just scared I guess.

 

[Quiksilver]

Still gonna need ground radials.... You might get away with a dipole sloper from the top of your mast to the ground.

 

[longhaireddwb]

How about a antenna that has shorter radials?

 

[Robb]

Depends if you are talking about a 50 ft push-up pole or a crank-up tower.

I can see you putting out a 10 ft horizontal boom on the 2/3 point overall height for the 2m/70cm antenna on a crank-up tower.
Solid idea.

But I wouldn't waste my time and trouble to put a 1/4 wave antenna on the top of a tower. I would run a beam with a single director on it, like a:
Gizmotchy G31 Antenna - Palco Electronics
Or maybe a:
Jo Gunn JG 3+3 Star - Palco Electronics
Or even a:
Jo Gunn Smokin Gun II - Palco Electronics

If a vertical is what you have in mind, then a:
Maco V/58 Omni-Directional - Palco Electronics

If it is a mast and not a tower; then I would choose the Smokin Gunn or the MacoV/58...

 

[555]

why go up 40 foot with the pole why not go 20 foot pole then the 20 foot antenna

 

[IMD262]

A99/I-Maxx - Easy up, decent performance

 

[longhaireddwb]

555 said: why go up 40 foot with the pole why not go 20 foot pole then the 20 foot antenna?
I live in a two story apartment building and at the 20 ft mark is the facia board of the building which is the bottom of the peak so to say. That is where I was going to attach this mast. I was thinking it would give me great stability that way. We do get some 60 mph winds around here a few times a years so stability is a big deal. So I will take the length into thought. If I go up to the 10 foot mark with the duel band antenna it could be installed on a four foot boom which will put the top of the antenna at the mast mounting point. It would not be above the building though but it is on the side of the building that the local repeaters are on (althought 15 miles away). Then I could mount the 11 meter on the top like the Maco.

Rob KI6USW said: Depends if you are talking about a 50 ft push-up pole or a crank-up tower.

I can imagine what a crank up tower is but I'm not sure what a push up pole is. What I got given to me is 3 10ft sections and 2 five foot sections of steal 1.5" diameter pole that slides inside each other about 6" to lock together.

I've been thinking about the Maco but how long are those ground radials? Someone with a Maco let me know would ya. If there like 9ft long than that's just not going to work. 2 - 3 feet long than I'll go for it.

I'm afraid that with the 9 ft long radials it will be way over the top of the duel band antenna and might mess with the performance of it.

BTW, thank for the link to the antennas!

 

[longhaireddwb]

Well I found my answer. The radials are 8.75 feet long!

 

[longhaireddwb]

If I go with the Maco I will end up with 2 of the ground elements hanging above the roof and close to touching the roof. The mast will be connected to the building at 18ft and be right next to the roof.The total length of the mast will be at 28-30ft. At that point the tip of the antenna will be at 50 ft.
Is this too much?
I'm just worried about everyone in the area seeing this antenna. As it will be seen from everywhere up there.

 

[Robb]

A99/I-Maxx - Easy up, decent performance

Can't go wrong with these choices either.
Might be easier to go with the A99 - on the basis of using many sections of 10 ft and 5 ft interlocking-type pipe. You would do well to adjust the SWR before putting it up permanently. Don't forget to guy any lengths that are unsupported over 10 ft with the antenna attached.

PS-Know where your power wires and power poles are - always!!!

 

[longhaireddwb]

Thanks for the info Rob.
I'm back to thinking about the 102" whip. The 20ft long antenna with the 9 ft long ground radials is just way too much. I'm in an apartment and that thing is just going to be sticking out big time! I'm thinking if I went with the 102 on a spring mount and put it on top of the metal mast it should work as a vertical Dipole. the ground element will be twice than what is needed and the upper element will be the whip and I'll cut it to set SWR. I can do this with it all together by standing on the roof and bending down the whip for cutting with it being on a spring. Also when the wind gets to kicking around 60+ I wont have to worry about it. Another thing is that I wont need to worry about guy wires as the top section will be mount to the building.

I know that the Imax or Maco will work better and get me more skip but I know if I put one up the people living in the apartment building are going to @#$%* and I'll have to take it down.

If anyone has an opinion as to why this wont work or can tell me why my idea is flawed in some way please let me know.

 

[Robb]

Any antenna can create interference - even a 1/4 wave whip.
I think that the A99 would easily be a better choice. But if money is an issue; then run what you got. You might want to make a coax choke for the thing.

Colorado Springs eh? I talked to a guy in Colorado Springs last night when skip was still rolling in. Think it was on 39/LSB, he heard me call my WR-11 handle and answered. Have a lot of operators in your area?

 

[longhaireddwb]

yep, theres a bunch here that like to clog up the air ways on 19 when the truckers are asking for help. That pisses me off. But on SSB i'm not too sure but I bet theres a lot. We have over 1/2 million folks in town.

Your still think a 99 would be better? I will think about it some more. if I could run one without the ground radials It might work.

Anyone else agree with the A99 working better than a 102" Whip?

 

[longhaireddwb]

OK Rob, I'm going with the A-99 w/no ground radials.

I hope I made the right decision. Oh well. I'll get it ordered tonight.

Thanks for the help with this.

A-99 on the top of the mast and a Diamond (300A) 2m/70cm at the half way point on a horizontal bar. Total will be around 38ft to the top of the A-99. Unless someone thinks I should go higher. I got the mast to do it.

 

[Robb]

OK Rob, I'm going with the A-99 w/no ground radials.

I hope I made the right decision. Oh well. I'll get it ordered tonight.

Thanks for the help with this.

A-99 on the top of the mast and a Diamond (300A) 2m/70cm at the half way point on a horizontal bar. Total will be around 38ft to the top of the A-99. Unless someone thinks I should go higher. I got the mast to do it.

Go higher if you have the masting and can safely support it with guy wires.