Antenna Poles

jp2code · 16-Nov-2010, 7:16 PM

I've noticed most Antenna Masts are just hollow pipes with the coax running along outside of them.

If it is a hollow pipe, why wouldn't someone run the coax through the pipe?

It seems like this would protect the coax from falling limbs or whatever.

Just curious. Maybe it's an RF/Faraday Cage thing.

John Candle · 16-Nov-2010, 7:33 PM

I have been putting coax in the mast for years , better then taping to the mast or letting the coax swing in the wind. The coax shield is grounded so having the coax in the pipe provides more shield. . Using a coax grounding block with a wire to ground such as a ground rod , or even if it is a metal cold water pipe that has metal pipe that goes into the ground to the water main is Ok. I say real metal water pipe because some pipe used now days is plastic. I have seen outside water metal water faucets with a short metal pipe that goes in to the house but rest of the piping in the house is plastic. Any way having the coax grounded diverts atmospheric static and interfering signals to ground.

jp2code · 16-Nov-2010, 8:08 PM

@John: LOL. Me too. I just wanted to check discretely instead of someone coming on here and flaming me for my ignorance.

rickcain · 7-Dec-2010, 5:06 PM

I've never even thought of that. While its not practical for antennas like the CM4221, I can see its perfectly fine for other clamp-on types, provided the edges are smooth or grommeted so the cable doesn't get sliced up from friction.

jp2code · 7-Dec-2010, 5:26 PM

I don't have a rotor, so my only vibrations are from residual earth quake vibrations in California that make it to Texas (i.e. not many).

Still, I think I'll ensure it has smooth edges the next time I'm up there piddling around.

Also, AFAIK a top rail from a chain link fence works just as good as a "real" antenna pole, and is cheaper because it isn't a specialty item.

GroundUrMast · 7-Dec-2010, 8:17 PM

Quote:

... a top rail from a chain link fence works just as good as a "real" antenna pole, and is cheaper because it isn't a specialty item.

I think better, I get more galvanize coating and heavier gauge steel.

John Candle · 7-Dec-2010, 10:45 PM

Is fine for the CM4221 , feed the coax up through the pipe and out the top of the pipe , loop the coax around and connect to the antenna. If the pipe has been cut to length , smooth the edge with some sand paper.

rickcain · 7-Dec-2010, 10:50 PM

I've tried chain link fence pole. Its almost the same size but not quite the same as an antenna mast in diameter...grrr. It is cheap stuff though, and masts are way overpriced as we all have found out.

The great thing about standards is there are so many to choose from.

John Candle · 8-Dec-2010, 12:30 AM

It's Ok to think creative. Does 'Top Rail Pipe' chain link fence pipe or any other pipe need to be the exact same size as antenna mast ? . The answer is No. More creative thinking , Use galvanized threaded pipe as a antenna mast and this Tee coupler # 510-606hc , bring the coax out the side coupling , and if you are concernd about the threads cutting into the coax then screw in a short plastic pipe. And for mounting 2 antennas , the same coupler turned the other way. And for mounting 2 or even 3 antennas , a 4 way galvanized pipe coupler. Thread pipe has couplers and adapters for different sizes.

jp2code · 9-Dec-2010, 3:42 AM

Hey John Candle,

Great idea, but...

Tower Guy · 9-Dec-2010, 2:26 PM

Quote:

Originally Posted by GroundUrMast

I think better, I get more galvanize coating and heavier gauge steel.

True, but the steel strength is usually lower with water pipe and conduit than mast. In most cases the difference in strength offsets the increased thickness.

The real issue is diameter. Most TV antennas are configured for 1 1/4" thick masts. Almost all pipe and conduit is 1.375" OD. Some U bolts fit easily, others don't.

ADTech · 9-Dec-2010, 3:40 PM

FYI, ALL of our outdoor antennas feature mast clamps that can accept up to a 2" OD mast.

I frequently suggest 1 1/4" EMT conduit to folks who need something right away. It's inexpensive (about $10 for a 10' section at most home centers and hardware stores), is moderately rigid (although is can be bent), and stands up to weather well.

Tower Guy · 9-Dec-2010, 9:46 PM

Quote:

Originally Posted by ADTech

FYI, ALL of our outdoor antennas feature mast clamps that can accept up to a 2" OD mast.

Thanks. If it ever comes up again I'll change "most" to "many except Antennas Direct". The wing nuts for the U bolt are a nice touch too.

The extra diameter of 1 1/4" pipe (1.66" OD) increases the strength significantly over standard TV mast.

I have my CM 4228 on 1 1/2" (1.9" OD) galvanized pipe. I built aluminum adapter plates to make it work.

kieths · 9-Feb-2011, 12:08 AM

I mounted a Winegard HD8200U on a 10 foot section of chain link fence pipe, using a chimney corner mount kit. It holds well, but the Front-To-Back rejection is giving me fits. I'm surrounded by both high and low powered TV stations here, and pointing it in ANY direction draws in a weak station 'here', while effectively shunning several 'there'.

The wife veto'd me getting a rotor / rotator. I used to have one, turned it enough times to annoy her, I guess ;-). So I decided on adding a second antenna (following her wishes to NOT get a rotator, I had no other choice but replace the rotator with an eyesore...not one, but two monster antennas. Se la vie).

The second antenna I added to the mess was a 'like new', open box Antennacraft HD1850, very heavily discounted at a local electronics surplus store. But to put two same-band antennas on the same pole, they have to be separated to avoid interference with each other.

The two antennas need to be separated by about 1/2 the wave length of the lowest channel used on either antenna. Channel 2 is about 54 MHz, with a wave length of 5.56 meters. Half of 5.56 meters is 2.78 meters, or 9.12 feet. So the booms of the two antennas need to be separate by just over 9 feet (or more). So....I need to get another pole!

Mounting the antennas at the right separation is the biggest challenge, but there is more. Both lead wires need to be the same length (to keep the two antennas in phase). To join the leads, I'm using a cheapy indoor TV signal splitter in reverse, hidden inside a weatherproof box mounted on the chimney. A single lead goes down to the TV for strong signals in both directions.

My worry? The two ten foot poles. If you've never looked at a fully assembled HD8200U, or an HD1850, you should look up the specs on them. The chain link fence pipe is pretty stiff, but only 3~4 feet hold onto the chimney, leaving the remaining 16~17 feet gasping to hold the two monster antennas like sails against the winds. Might have to have the 'guys' help on this one eventually...

Ynot713 · 12-Apr-2013, 2:39 AM

Anyone have any opinions on using a 1 1/4" 10' EMT from Lowes with a "Ronard 4560 Adjustable Universal Eave Mount (4560)" to mount a "Winegard HD8200U"?

My plan was to have about 2' below the peak braced by the eve mount and then 8' above the peak.

It seems pretty sturdy and much heavier and sturdier than the RCA 5' swedged masts that they sell with the RCA antennas.

I know there is better stuff out there. Just wondering if this would work. It gets windy here sometimes but were not talking like gale force winds or anything. I'd say the most we've gotten is 30-40 mph gusts and that's a rarity.

I've been trying to figure out the actual gauge of the tubing but cant seem to a direct answer. Someone posted in the Q & A that its a little less than 1/8" thick. Here's the link: http://www.lowes.com/pd_72717-1792-1...ductId=3129557

Thanks.

ADTech · 12-Apr-2013, 4:36 PM

A Google search says that 1.25" EMT should have a wall thickness of .065" which should be around 16 gauge. http://www.westerntube.com/electrica...lic_tubing.htm If you need something heavier , there's also 1.25" IMT (.095 nominal wall thickness) or 1.25" RSC (.133"), both of which are approx 1.5" to 1.7" in OD.

Quote:

FYI, ALL of our outdoor antennas feature mast clamps that can accept up to a 2" OD mast.

Updating this as our new DB8e is an exception. It will fit up to a 1.75" OD mast, a change necessitated by the mounting hardware scheme and the combiner box that was used.

Ynot713 · 12-Apr-2013, 5:56 PM

So do you think a 1 1/4 EMT from Lowes will be a sufficient antenna mast for a large outdoor antenna 8' above peak?

ADTech · 12-Apr-2013, 6:22 PM

If guyed, yes. Those 10' x 14' conventional antennas present a lot of wind load.

13-Nov-2019, 8:24 AM

Quote:

Originally Posted by jp2code

I've noticed most Antenna Masts are just hollow pipes with the coax running along outside of them.

If it is a hollow pipe, why wouldn't someone run the coax through the pipe?

It seems like this would protect the coax from falling limbs or whatever.

Just curious. Maybe it's an RF/Faraday Cage thing.

I'm going to be installing an F.M. antenna on an outbuilding in the near future and I had the exact same idea. What I have done so far is I bought a 10' section of 1/2" galvanized rigid metallic conduit (1/2" because it's going to mount directly to a standard electrical box with 1/2" knockouts) that's threaded at both ends. I then bought a galvanized 1/2" coupling and a strain-relief connector (A.K.A. a cable gland), and I fed some standard RG-6 coaxial cable through the conduit, out through the strain-relief connector (which I then tightened to ensure it is raintight), through a small clamp on the antenna boom, and then into the antenna's balun's F connector after crimping on a compression connector.

I've seen a lot of people suggesting that the cable run directly out of the top of the conduit. Personally I would avoid this, as it basically causes rain to end up in... places, i.e. you'd be opening an ugly and expensive can of worms. I would cut pipe threads in the top of the pipe, and then install a proper coupling and compression-ferrule connector so that water doesn't leak into the mast.

Better yet, if you've got some caulk on hand, I would then caulk all areas where water ingress could become an issue, including the connector boot, the strain-relief connector, the twin-lead bolts on the antenna's dipole (if they are exposed), and so on.

Hope this helps and good luck with reception!