30 Ft Tower

[pawsrock]

I have a 30 ft tower that was given to me a couple of years ago. Three 10 ft sections, my question is this. I believe using line of sight how far away would I receive a signal? I know the atmosphere will play into this, but I am just wondering with normal conditions. I am wanting to know, to see if I want to go through with this. Do not want to put it up and not be happy with it.

Area is Jacksonville Florida and I live in Duval county and I am scanning with a pro-2096 Jacksonville is a digital system and so is the beach. But surrounding counties still use UHF / VHF

Thanks
Ron Fone

 

[DPD1]

Unfortunately it's impossible to know because what each transmitter is doing at their end has to be factored in too... The height, antenna, power and so on. I can't imagine being up 30' would be bad under any circumstances, but how much better it would be compared to just on the roof or something, is very hard to know.

 

[RADIOGUY2002]

Police Call

Police Call book had a good reference point to start at, the higher the better in most cases. Sometimes it can come back to bite you in the butt with directional systems. Your next issue is the feeder line, make sure you spend good money for a quality cable run. Also, realize that hilly areas and water based areas will effect your range just as well as open fields by airports.

 

[davidmc36]

Use this and it will give you the line if sight to your horizon. Obstructions, environment, power of signal and height of second station will all play a factor in whether you can actuall recieve a transmission from there.

VHF/UHF Line of Sight Distance Calculator

For example your station at 30ft plus somebody else's at 30ft gives you 16 miles total distance to the horizon.

You may find many things you are listening to on a scanner are on towers much higher than that. If it is coming off a tower that is 200ft high your 30ft tower can just see one that is 28 miles away.

 

[RADIOGUY2002]

Thanks, for providing him with the chart. It's theory which is good, but not accurate as we who have been in the hobby understand. Conditions are what is a huge factor in this, so now I can understand why people get mad when you ask terrain coverage based questions. It's not really a fair based question, however is proabily the most asked question and for good reason. Allthough 800hz systems seem to shoot the theory dead in the water comptily which makes it very funny and quite aggervating at the same time.

 

[davidmc36]

Thanks, for providing him with the chart. It's theory which is good, but not accurate as we who have been in the hobby understand. Conditions are what is a huge factor in this, so now I can understand why people get mad when you ask terrain coverage based questions. It's not really a fair based question, however is proabily the most asked question and for good reason. Allthough 800hz systems seem to shoot the theory dead in the water comptily which makes it very funny and quite aggervating at the same time.

Well the chart does say VHF/UHF which is what he asked about so the reference to 800mhz doesn't seem to really apply here. As far as "theory being good", that's exactly what it is, for lack of a better term, theoretical line of sight to the horizon, which is why I included the comments "Obstructions, environment, power of signal.......will all play a factor in whether you can actuall recieve a transmission". For the record I recieve VHF Moto II Digital system perfectly clear from a tower that is 200ish high and is 45 miles away.

 

[pawsrock]

Thanks everyone for the help!! I would love to be able to put up something a little bit higher but I do not have the room for guywires.
Ron Fone

 

[RADIOGUY2002]

davidmc36

It was not to question you by no means, I was trying to support your statement. Vhf and Uhf Trunking systems seem to follow the line of sight pretty well. Excpet for the systems with bi-directional or "in house" based systems. Catered for on site comms only and not wide area, internal comms if you will. Over all kinda interseting to be able to play with and understand. Their is a system here by me that sits on a 100ft building and sounds like crud for wide area and it really should not. If your close it sounds pretty good, but the design or the systems user need wide area coverage not in house site based. Their not educated on radio theory and thats why they can't firgure out why their system sucks for wide area coverage. Not to mention their coax cable dates back to the 80's, so theirs heavy loss in the feed line. The system is used 24/7 and the repeater rated at 40 watts and erp is 22 watts and sits about 10 ft away from the repeater. You tell me whats wrong with that picture.

 

[buddrousa]

Ron for your information a rohn 25 tower will free stand 30 feet above a brace. If your house is 20 feet above the ground a house bracket at 20 feet to the tower and 30 feet of tower above the house bracket means you can have a 50 foot tower that is if you have the base of the tower in a 3 foot by 3 foot by 3 foot hole and a cubic yard of concrete in the hole. I have put up several of these with either a DB420 or 21 foot station master antenna on the top but that is about all the wind load the tower wants to see.