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100' run for aviation base station at heliport

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Dec 26, 2004
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New Jersey
#1
New hanger being built at work and we will be building a new antenna farm on the roof. Primary radio is a Technisonic TBS-350 aviation band base station. It has a built in linear amp and outputs 25 watts. It looks like it should be a 100' run from the operations room to the roof. Our previous installs we have always used LMR-400 but this will be a permanent installation vs our temporary trailers we were based in so want to do it right. We will have 2'' pipe run from roof down to first floor with no bends, from there above a drop ceiling the coax would run to the operations room where it will drop down an interior wall and then exit and terminate at the radio.

Roof will have unistrut mounted on a parapet wall and a 16x16x8 NEMA 4 enclosure will be mounted to 2'' pipes to house the lighting protection and then transfer from roof to inside the building.

Using the online loss calculator shows LMR600 putting 20watts out after loss vs the 25 in. To get better than that you have to step up the LDF5-50A which gives 22.5 watts or go nuts with LDF6-50A which give 23.26 watts. The two of us doing the install are very familiar with the LMR400 so leaning towards the LMR600 vs the hardline products which we haven't used before. I might have answered my own question but what do you think?


Also this will end up in a separate thread but we are going to remote control the radio. It has a tone control board built it allowing 2/4 wire, DC/ tone keying. Buying LE20 from CPI remote desk controllers and installing them at everyone desks throughout the office.
 
Joined
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10,045
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Point Nemo.
#2
LMR-600 might be a good option if that is what you are comfortable with.

You won't be able to tell the difference between 20 watts, 22.5 watts or 23.26 watts. The additional 2.5 or 3.26 watts isn't going to translate into anything noticeable.

Also, the LMR-600 is more flexible and easier to run.

LDF5-50 is going to barely fit in the 2" conduit. I don't think you are going to get LDF6-50 in their at all.
Keep in mind that you need to have a ground wire running from the protectors down to the building ground. If you were hoping to fit a #6 ground wire in there, you're really only going to be able to fit the LMR-600 or LDF4-50 in the 2 inch conduit.
 
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So Cal - Richardson, TX - Tewksbury, MA
#3
For antenna grounding on a commercial building it would be legal to run #10 copper wire from the antenna to a grounding clamp on the closest metallic conduit on the roof not to exceed about 30ft. That is assuming there are electrical runs on the roof using metallic conduit with home runs to the building electrical box.
prcguy



LMR-600 might be a good option if that is what you are comfortable with.

You won't be able to tell the difference between 20 watts, 22.5 watts or 23.26 watts. The additional 2.5 or 3.26 watts isn't going to translate into anything noticeable.

Also, the LMR-600 is more flexible and easier to run.

LDF5-50 is going to barely fit in the 2" conduit. I don't think you are going to get LDF6-50 in their at all.
Keep in mind that you need to have a ground wire running from the protectors down to the building ground. If you were hoping to fit a #6 ground wire in there, you're really only going to be able to fit the LMR-600 or LDF4-50 in the 2 inch conduit.
 
Joined
Dec 26, 2004
Messages
9
Location
New Jersey
#4
We will have a metallic conduit right next to the NEMA enclosure for our obstruction lighting so we could tie right in there. I have to look up the rules but if they bonded the ground with the steel frame of the building I think we could tie into the steel but I'm 90% sure I cannot. Otherwise we would go all the way back to the water main, additional ground rods nearby are not feasible. I figure use the NEMA box for mounting a thick copper plate that the polyphasers can be bolts to and the ground can attach to.

I have to check the plans, we requested (4) 2'' diameter pipes, 2 of them going to the first floor, 2 going to the second floor. No turns, just straight down into the building.

Total plan includes 4 antennas and space for future growth. We have our primary radio the 25 watt TBS-350, a backup probably a basic 8 watt Icom, a scanner that will drive a liveatc feed and then space for another antenna, those are just for our company.

Then we are doing an additional antenna for the heliport itself which only needs reception in a 1-2 mile range so not very concerned about getting a lot of reach out of that one.

I agree LMR-600 will probably be our choice, probably get the ultra flex so no issues making the turns for the lightning protection polyphasers in the NEMA box. Just need to stock up on the N connectors and get the right stripper tools for that, only have them for LMR400.
 
Joined
Jun 30, 2006
Messages
7,341
Location
So Cal - Richardson, TX - Tewksbury, MA
#5
Grounding to an existing metallic conduit on the roof would satisfy NEC for safety grounding. If you want or need to ground for lightning protection that's a different subject and you should contact a professional company that specializes in lightning protection. That is usually beyond what employees can do and if the company expects to survive a direct lightning hit and it doesn't then you don't want to be blamed for a failed design.
prcguy


We will have a metallic conduit right next to the NEMA enclosure for our obstruction lighting so we could tie right in there. I have to look up the rules but if they bonded the ground with the steel frame of the building I think we could tie into the steel but I'm 90% sure I cannot. Otherwise we would go all the way back to the water main, additional ground rods nearby are not feasible. I figure use the NEMA box for mounting a thick copper plate that the polyphasers can be bolts to and the ground can attach to.

I have to check the plans, we requested (4) 2'' diameter pipes, 2 of them going to the first floor, 2 going to the second floor. No turns, just straight down into the building.

Total plan includes 4 antennas and space for future growth. We have our primary radio the 25 watt TBS-350, a backup probably a basic 8 watt Icom, a scanner that will drive a liveatc feed and then space for another antenna, those are just for our company.

Then we are doing an additional antenna for the heliport itself which only needs reception in a 1-2 mile range so not very concerned about getting a lot of reach out of that one.

I agree LMR-600 will probably be our choice, probably get the ultra flex so no issues making the turns for the lightning protection polyphasers in the NEMA box. Just need to stock up on the N connectors and get the right stripper tools for that, only have them for LMR400.
 
Joined
Feb 11, 2009
Messages
525
#7
For any permanent installation, heliax is the only way to go and 1\2 inch heliax is plenty for your purpose
 
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