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Author Topic: Antena Question  (Read 4063 times)
KA4NMA
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Posts: 348




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« on: November 25, 2012, 11:58:55 PM »

I live in an  apartment complex made up of duplexes (4 apartments per building) and live in the end unit. The have antenna restrictions.  I am also disabled.  My doctor wrote a note requesting the complex allow me to put up an antenna as part of my treatment plan.

What I am thinking off is 1 of 2 antenna's.  I will be using a SGC tuner.  Both antenna's will be random, and of a decent size. And placed around the eaves of the house, just below a metal run gutter. that runs along the front of all 4 apartments. I am planning on some sort of small gauge wire that is stealthy.  My next door neighbor is on oxygen.  I have no trees around.  I have a choice of either using an Icom 706MKII (it does not have 70cm) or a FT-817ND.

The front of the building has a few turns and recessions, so it is not flat.  My shack is in the bedroom which is on the front of the building. I will be using low power and I am interested in covering 75m-6m (which the tuner covers).  I  want to get back into ARES HF nets, ragchewing, dx hunting, digital modes and trying the magic band.

Antenna 1 is a random wire going from the front of the building, around the side and back.  I will place radials all around the bedroom.  It will be roughly u shaped.

Antenna 2 is has the same run as antenna 1, but will continue over the roof, laying on top of asphalt shingles, forming a loop.  The roof has a peak so the antenna will go up and then come down and pass over the gutter.

What are the safety issues of both antenna's, such as rf field safety, fire hazards, etc.  What is the rfi concerns? Which would have a better efficiency and performance? How close to the gutters can I place the antenna? What will be the effects of the asphalt shingles?  What is the max power I could run?

Randy Ka4nma
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WX7G
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Posts: 6129




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« Reply #1 on: November 26, 2012, 05:36:17 AM »

You will get many answers including suggestions for different antennas.

This link to RF Safety articles and calculators will help you design your antenna so it does not subject the neighbors to RF levels over the limit.

http://www.arrl.org/rf-exposure

The antenna run right along the apartments is a recipe for excessive RF exposure on the higher bands and RFI. I suggest placing the antenna away from the apartments. A screwdriver antenna in the yard would be good and a Tarheel 100A with a 6' whip is only 10' tall and covers 80-10 meters (I have a Tarheel 200A in the yard). My antenna is mounted like the one shown in the third photo; a length of 4" x 4" hollow plastic fence post is slipped over it and a bird house is mounted on the post.

http://www.tarheelantennas.com/base_installation_photos

http://www.tarheelantennas.com/mobile_antennas

Given the two radios you mention the Icom would be my choice. The FT-817 is only 5 watts and while you will make contacts it will be some work. On the other hand with 5 watts any concerns about RFI and RF exposure go away. In that case run the antenna wire around the apartment and make it 65' or longer.

« Last Edit: November 26, 2012, 05:39:06 AM by WX7G » Logged
KA4NMA
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Posts: 348




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« Reply #2 on: November 26, 2012, 09:06:30 AM »

Placing an antenna in the front yard is not possible. The yard is very small and is next to the main road in and out of the apartment complex.
Randy
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WX7G
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« Reply #3 on: November 26, 2012, 12:29:38 PM »

Then the wire antenna you mention is in the running as is a Buddipole and a medium size loop (MFJ-933 loop tuner) inside the apartment. Another thing some hams do is mount a screwdriver antenna on the car and run coax into the apartment.
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KA4NMA
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« Reply #4 on: December 07, 2012, 04:27:37 PM »

I am still waiting on a response about running the wire on asphalt shingles.

Randy Ka4nma
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WX7G
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« Reply #5 on: December 07, 2012, 04:48:22 PM »

I have run insulated antenna wires in direct contact with asphalt shingles many times with no problems. The power level was 100 watts.
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K5LXP
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« Reply #6 on: December 09, 2012, 08:06:01 AM »

I am still waiting on a response about running the wire on asphalt shingles.

The problem isn't the shingles, it's what may be underneath them in the form of metal roofing or other construction material.  You can't predict what will happen, you just have to try it and see.  From there, it's up to your expectations whether it's adequate or not.


Mark K5LXP
Albuquerque, NM
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