Thank you Stampeder. I'm assuming that using some kind of plastic "collar" or spacer between the aluminum tubing and the steel wall brackets and antenna "grip" would prevent the galvanic corrosion from happening. If not, perhaps a thinner gauge steel tube would do...

You can save yourself a lot of trouble (and corrosion) by just going with galvanized pipe for the antenna mast and then hot dipped galvanized nuts, washers, and bolts. If you use galvanized with plain steel you're still okay if you rust-proof the steel as best as you can.

Seems like galvanized steel tube is the simplest way to go. I'm also guessing that aluminum tubing would be more expensive than steel. Any guidelines as to what the minimum wall thickness should be for an 1 1/2" OD tube at least 10' long (or perhaps 1 1/4" tube)? I would like to keep it as light as possible, obviously without compromising the stiffeness. I'm not sure how comfortable I will feel standing at the end of a 20' long ladder holding long piece of heavy pipe in one hand =) I guess we'll find out soon enough. Thanks again.

Thanks Holl Ands for the great post. Did quite a bit of reading from all the links, and I am convinced I will have good stations, especially being located along the US/ Canada border. Will do a roof installation this spring, after the bugs are gone.

I avoid installs on the roof over time shingles warp and even if you sealed it, it can cause a leak, i agree it can be done but why put yourself at risk for a future leak! I normally use a eaves mount or pole mast with a 12 or 18 inch wall mount so i can mount on the side of the house and still get roof top height!

alander,

I'm not sure how comfortable I will feel standing at the end of a 20' long ladder holding long piece of heavy pipe in one hand =) I guess we'll find out soon enough.

I hope for your sake you are not serious....you dont want to learn the hard way...what I did before mounting any masts, I tried to lift a 5 lb mallet (3 ft shaft) with one hand at the end of the shaft and the head straight up in the air...try that and you will quickly realize what you're contending with...

This is one of the reasons I went with the aluminum, i'm not worried about corrosion, it will take a long time to happen...(time will tell!). I just dismantled a 30 ft tower, all galvanized, and all the brackets gavanized or not were corroded along with parts of the tower...the gavanization wears off with time and any corner or joint will corrode first also...an installer told me its primarily due to acid rain...

Another option maybe a telescoping mast. I made one so I didnt have to prop up the mast, and antenna...

stampeder,

I tried restoring that old tower. I used CLR on the rust and had limited success.

Have you seen any rusted, galvanized towers which were subsequently painted with say a Tremclad and primer for galvanized, and if so how durable is that going to be...an installer told me after a year or two, it will look like "speckled trout".....


thanks

The "speckled trout" look is from the crystalization of the steel with the zinc. I had a friend who worked at Dofasco in Hamilton, ON who used to work in the galvanizer plant. Huge sheets of steel were rolled into a pool of acid and zinc, then when it was all immersed the sheet was cut so that it fell into the bath, then after a few moments WHAM! a collosal jolt of electricity was blasted into the pool and in only just a second the sheet steel showed the zinc crystalization look, meaning that it was now galvanized.

Anyway, I don't have any problem with cutting, trimming, or wire-brushing old galvanized steel to clean it up, but I choose not to arc weld it due to the dangerous fumes created at those high temperatures. Like with aluminum, there's no point in painting it unless you prime it first with the proper type of primer.

stampeder,

thanks for the information.

I think he also was referring to the fact (according to him) that any paint will chip off bit by bit, and make the tower a real "eye-soar"....I wouldnt want it to look worse than gavanized steel with some rusting...

I read up your post on galvanic corrosion with great interest...thank you...

I was thinking if I should use a little white grease between the aluminum mast and any dissimilar fastners to inhibit the galvanic corrosion...

When I install the tower base section, can I just set into the ground 1 or 2 ft, or does it have to be set into say, concrete, or again, do I have to use a plate at the base with angled pegs into the ground in addition...

There are lots of warnings on the web about simply burying the lower part of a tower in concrete or dirt, because they aren't designed for the physical stresses found at the very bottom. A base plate is designed for that.

I was thinking if I should use a little white grease between the aluminum mast and any dissimilar fastners to inhibit the galvanic corrosion

I work in the auto industry and deal with galvanic corrosion protection all the time. You need to electrically isolate the two metals to prevent it. Grease will not work because it will get squeezed out when you clamp everything together and create small contact areas between the steel and aluminum. We usually e-coat steel parts that come in contact with aluminum and that thin barrier is enough to stop the corrosion. You could probably get away with a good paint job on the steel parts, making sure to use a good primer designed for use on the galvanize.

You could get more elaborate and make some plastic bushings, or going the cheap way you could wrap electrical tape around the pipe before clamping it. Not sure how long the tape would last, and it would probably reduce your clampload and loosen over time, so I wouldn't really recommend it.

You could get more elaborate and make some plastic bushings, or going the cheap way you could wrap electrical tape around the pipe before clamping it.

Heat shrink tubing might work as well. Just speculation though and not sure how long it would last, but it should be better than electrical tape.

I came across this Antenna Installers Guide from Channel Master.
{You will need Adobe Reader to view it.}
http://www.solidsignal.com/manuals/AntInstallGuide.pdf

It's a few years old now.
But for those doing they're own antenna setups.
There is a lot of good information that still applies to setting up your OTA system.


Signed: Janitor Tzap

I avoid installs on the roof over time shingles warp and even if you sealed it, it can cause a leak, i agree it can be done but why put yourself at risk for a future leak!

And what about having to replace your shingles? A roof lasts for 20 years or so, but if you are in a house with a 15 year old roof and you install over them, you may have to take your setup down and do it all over again when you replace the shingles in a few years. My antenna's in the attic for now, but if I decide to go outside I would definitly mount to the bricks.

The other consideration is running the cable into the house. If you want the cable in the basement the easiest way is to run down the outside of the wall, which is perfectly suited to a brick mount. If you mount on the roof you have to somehow fish the cable all the way down to the basement, which may or may not be easy to do.

you may have to take your setup down and do it all over again when you replace the shingles in a few yearsOr if you had a sudden roof leak and called roofers to come over, can you trust them to put all your OTA gear back properly? I'd have to say no on that, no offence to roofers.

Yeah,
The idea of having to get back up on to the roof,
reattach the mountings for the antenna mast, plus realigning the antenna.
As well as the grounding wire for the mast, isn't that appealing too me either. ;)

I wish I could remember where I saw this roof top mounting system for a J mast.

Basically, it replaces the old Roof Top Air Vent with one that has mounting bolts for a J-mast that can be attached on top of it.


Signed: Janitor Tzap

Just got back from my lake house in upstate NY, and I moved my antenna in the attic, from the center of the attic to 16" from the exterior wall. I took someone's advice from this forum, and WOW, what a difference. Lucky for me, the gable end is in the direction of the main towers.

My TV's signal meter went from below 40%( couldn't lock on to channels) to 81% and great picture. This is simply moving my 8228HD about 10' foreword. I can say, having a sloped metal roof, really blocked signals in my attic, upto 50% compared to placing against the exterior wall. Plus, many Canadian channels come in pretty good from Mt Orford.

Guess my next step will be putting a 10' mast outdoors above my roof , once I gather all my materials.


Thanks for everyone's feedback, this a fun new hobby for me.

That's great news, bucyluca, and it sure shows what influence a metal roof can have!