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Transmitter Site at Water Tower
- Thread starter bigdummy
- Start date
More specifics needed. The one BIG question for starters is AM or FM?
George Kowal CBNT
Assistant Chief Engineer
Press Communications, LLC
d/b/a
G Rock Radio 106.3 WHTG-FM & 106.5 WBBO
The Breeze 107.1 WWZY & 99.7 WBHX
K 98.5 WKMK Real Jersey Kountry
Real Oldies Music 1410 WHTG-AM
George Kowal CBNT
Assistant Chief Engineer
Press Communications, LLC
d/b/a
G Rock Radio 106.3 WHTG-FM & 106.5 WBBO
The Breeze 107.1 WWZY & 99.7 WBHX
K 98.5 WKMK Real Jersey Kountry
Real Oldies Music 1410 WHTG-AM
bigdummy said:
How many bays? What polarization? How high will the lowest bay be above the top of the water tower? If this is a licensed, US FM station then will the height and location of the water tower and radiation center of the antenna allow meeting the FCC license/construction permit?
Sorry guys for being too vague. My question is: What is the best way to handle an install at a water tower? We were thinking we would need some type of 10-20 foot pole/section of tower and mount it on the very top of the tower. With it only being a 500 watt station, we could probably get by with just one bay, possibly two. What factors would you consider?
C
CW
Guest
bigdummy said:
With one element and 500watts, you could mount on a pole that was welded on the side of the water tower and goes above the top. I have a LP client that did that..works good and though their element does NOT clear the top of the tower, they have fairly good coverage for 100watts. (the null was planned anyway)..I take it this water tower is round at the top ?? Does it have an access hatch or any place to mount a short pole (2in or bigger?)...YOU COULD mount on top but make sure you are 5-7ft above the top of the water tower...you dont want any reflections off of it skewing your pattern up! Dont need to be 10-20ft
Be aware of a potentially expensive problem. Not uncommon to see two-way antennas mounted on water towers. Usually for base stations for the government entity that owns the water tower. However, I've heard from two-way guys that, over time, circulating currents (from the RF) can damage the interior of the tank, even eat a hole in the tank.
It's one thing if the water district has to fix the tank because the Volunteer FD radio causes damage--they'll work that out internally.
It's another when the water district finds that it is your FM station that caused the problem. Guess who's pocket they will want to empty.
I think I would pass on this site.
It's one thing if the water district has to fix the tank because the Volunteer FD radio causes damage--they'll work that out internally.
It's another when the water district finds that it is your FM station that caused the problem. Guess who's pocket they will want to empty.
I think I would pass on this site.
I have not heard about the problems of circulating currents causing problems but I can tell you that if you do mount an antenna on the water tower be sure to check with the tank contractor or engineering firm before you do any welding on the tank. Some tanks are coated on the inside with some form of special epoxy paint and the heat from welding can damage the paint. Many $$$ to repair. We were mounting a bracket for a two-way antenna for the water works when they informed us of this. If the tank does not have a moving ladder you may be able to make a mount to fasten to it. We used a steel plate with a 6 foot pole welded in the center and stainless U bolts to clamp it to the ladder. The ladder may not be flat on top of the tank. Check the angle so you can make the pole straight.
It would be wise to be certain that the antenna is above the water tower. With a side mount, a solid blockage behind the antenna will result in a huge null. And while I haven't seen it in the FCC Rules, I have read more than once that the FCC will not knowingly license a non directional FM side mounted on a water tower because the pattern would be far outside of what they consider to be non directional. Not to mention that, short of an expensive pattern study & custom mounting brackets, FM antennas work best when there is a minimum of metal near then. The 2" OD pole described by an earlier poster on this thread would provide an ideal mount for a single bay. Try to shoot for 20' above the top center with 10' an absolute minimum.
A lot of that depends on the bay. I put a single bay up for a translator a couple weeks ago and felt quite confident using TV masting...but the bay weighed 3-4 pounds. On the other hand, there are bays that weigh (this is an educated guess) upwards of a hundred pounds--maybe more. Remember that there will be more wind on top of a water tower than on a rooftop at a typical house. Still, if what you're thinking about will stand the test of time with a huge VHF TV antenna (the kind that's perhaps 12-15' long) on a 2 story house, it would likely be adequate to hold a 3-4 pound FM bay on a water tower. Just don't make the mistake of adding a tall mast on top of the mini-tower. A 5' TV mast (with 1-2' of it inside the tower) for mounting is all I would go for.bigdummy said:
Don't forget RFR safety requirements. Kids like to climb water towers & tag them. It's a tradition.
C
CW
Guest
bigdummy said:
Where abouts in the South?
Several FM's mounted on water towers.
In the case I have viewed the site was available and worked.
No worse than mounting on a 10 foot face tv tower and using the tower to affect the signal.
The FCC takes a dim view on using a structure to manipulate the signal,,,right,,,when? This is a misconception with no basis in fact.
No NAL no forfeiture and the pattern people do good business. Unless you use a parasitic and the structure is not a parasitic.
Can I quote Jack Mullaney? "Is it good engineering practice? Is it poor engineering practice?" Jack can be hired to provide an analysis of such previous installs where this has been determined to be acceptible.
Mount the antenna on the handrail towards the city you want to cover. Mounting on a building, or even at a location where the earth affect the signal is somewhat an act of God. Empire State Bldg?? There are many lower antennas.
In Indy the top of the Bank One Bldg is a set of dual water towers which were fabricated to form pylons. Kennedy tank and tower. Several Fm's have used these with no restrictions due to the effect (desired or undesired) on a station's rf footprint.
Many water towers near here have a set of poles on top of the towers for any type of antenna. Aimed at the cell market.
Make sure your cables are weld grounded top and bottom. Most towers are on high points for water pressure. What a great antenna site. Be prepared to go off the air when it's painted. Still an rf concern.
A 30 foot round structure and 2 bay antenna could create an unintended 9 to 12 db boost in the direction the bays are mounted. Can kill most signal the other direction.
In the case I have viewed the site was available and worked.
No worse than mounting on a 10 foot face tv tower and using the tower to affect the signal.
The FCC takes a dim view on using a structure to manipulate the signal,,,right,,,when? This is a misconception with no basis in fact.
No NAL no forfeiture and the pattern people do good business. Unless you use a parasitic and the structure is not a parasitic.
Can I quote Jack Mullaney? "Is it good engineering practice? Is it poor engineering practice?" Jack can be hired to provide an analysis of such previous installs where this has been determined to be acceptible.
Mount the antenna on the handrail towards the city you want to cover. Mounting on a building, or even at a location where the earth affect the signal is somewhat an act of God. Empire State Bldg?? There are many lower antennas.
In Indy the top of the Bank One Bldg is a set of dual water towers which were fabricated to form pylons. Kennedy tank and tower. Several Fm's have used these with no restrictions due to the effect (desired or undesired) on a station's rf footprint.
Many water towers near here have a set of poles on top of the towers for any type of antenna. Aimed at the cell market.
Make sure your cables are weld grounded top and bottom. Most towers are on high points for water pressure. What a great antenna site. Be prepared to go off the air when it's painted. Still an rf concern.
A 30 foot round structure and 2 bay antenna could create an unintended 9 to 12 db boost in the direction the bays are mounted. Can kill most signal the other direction.
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