That looks like a pretty nice job from the pictures.

Otherwise, the rod and one side of the aluminum could be given a very thin coat of contact cement, which is waterproof,
Its somewhat waterproof, but not UV resistant, so it will let go in time. Some GE adhesive clear caulking Ive found is supposed to be good for 50 years outdoors (so it says). Another option is a few short pop rivets.

They do not mention anodizing, but claim that the tube is protected by an "accelerated aging" process.
Heh, what they may mean is that aluminum oxide (that white dust stuff) has formed on the surface. Technically, when oxide forms on the surface, it does somewhat protect the metal underneath, including in the case of rust (iron oxide).
Gain wise, the oxide coating slightly reduces the velocity factor as in the case of a thin coat of paint.

After making just three tubes by drawing strips of thin aluminum flashing through holes in a piece of wood, I have some ideas that should make the tubes come out really well. The entry side of each hole would be tapered. The hardwood draw plate would be a couple inches thick, with the final straight part of the hole an inch or more long, which would encourage the metal tube to come through the hole straight. It is also necessary to pull the metal out straight. A cord running over a pulley that is lined up with the draw hole would keep the metal moving correctly. A sharply pointed dowel would be fed in as the metal is drawn through each hole, a different size dowel for each size hole. The dowel would push the metal against the inside of the draw hole, which would help make the tube smooth. My first attempts tended to have the metal edges crinkle at the tubes' open seam.
I do not believe that tubes made from Al flashing, which mine measures 0.010" thick, would withstand high winds, especially with the tubes having an open linear seam, and especially at the 1/4" tube diameter. Annealing the tubes might make them less bendy. However, it should also be possible to draw a second tube around a finished 1/4" drawn tube, with their seams on opposide sides, to make a much stronger tube. I would think that would be strong enough for antenna work, but if not, a third tube could probably be drawn over a double, yielding a really strong tube. Slightly larger holes would be needed in the draw plate for a double and triple.

However, it should also be possible to draw a second tube around a finished 1/4" drawn tube, with their seams on opposide sides, to make a much stronger tube.
Why not just wrap/roll it twice over the 1/4" rod for extra strength ?

Unclesam will post instructions on how to vapor-deposit copper onto fiberglass rod.

Pep Boys did (or still do ?) sell a galvanizing spray paint used to touch up boat trailers etc.
I never bought any, so I dont know its conductivity.

MikeInMKE, not how to vapor deposit copper onto fiberglass rod, but how to copper plate fiberglass rod. Industry routinely electroplates onto plastics. Brush the rod with suitable adhesive, dust with carbon dust or copper dust. Electroplate using hard copper. I found kits on the Internet for doing this, but the chemicals used are too harsh for me to deal with at home. The initial equipment cost would be too high to justify for making antennas, but a shop that already does electroplating (local motorcycle customizer) might be willing to give it a try. Still, probably not worth the cost unless someone wanted to make them in quantity to sell.

If tubes for GH antennas made by rolling aluminum flashing are not strong enough to support themselves during high winds, it may be possible to make them stronger by filling them with minimal-expanding closed-cell foam. One commercial antenna manufacturer touts its line of wind-resistant antennas, mentioning that the tubes are foam filled. Foam is available at home centers in small pressurized cans, different grades of expansion and hardness.

it may be possible to make them stronger by filling them with minimal-expanding closed-cell foam.
Thats an idea. The foam is also an adhesive, keeping the tubes together. But because the foam expands, it will need to be placed inside of another tube. Also, the ends of the tube will need to be sealed as the sunlight really destroys that foam in a short period of time.
The foam may lower the velocity factor of the rods, but only by an insignificant amount.

In stock at a Home Depot, a couple of miles from my house. I'll run over there during lunch and pick up a can and some fiberglass rod (assuming they have any).

Anything besides conductivity that I should be measuring?

Wear gloves when using that stuff! You don't want to be doubled over with Zinc toxicity. :eek:

I'll wait for the weather to improve (it's raining) so I can spray the rods out doors, with gloves and a mask.

Anything besides conductivity that I should be measuring?
Mainly conductivity. Zinc isnt the best conductor, but for reflectors its OK. I wouldnt use it for driven elements though.

About all we can do is compare zinc to some other metals. Zinc isn't a terrible conductor, but it isn't the greatest, either. Perhaps it might be best to classify it a fair as regards electrical conductivity. Here is a list of just a few metals and their electrical conductivity as "just a number" to make comparison easy:

Aluminum 59
Brass 28
Copper (annealed) 100
Gold 65
Lead 7
Mercury 1.66
Platinum 15
Silver 106
Tin 13
Titanium 5
Tungsten 28.9
Zinc 28.2

Zinc isn't great, but it isn't at the bottom of the list, either.

Read more: http://wiki.answers.com/Q/Is_zinc_a_good_electrical_conductor#ixzz1POljxQoM

I picked up a can of Rust-Oleum Cold Galvanizing Compound, but Home Depot does not stock quarter-inch fiberglass rod. I'm pretty sure I can get some in the electric fence isle at Fleet Farm. Next time I'm out that way, I'll pick some up.

MikeInMKE, every Home Depot and Lowes I have visited sells the 5/16" dia fiberglass rod in the section that has driveway markers having round reflectors on their tops, in the display of plastic lawn signs, stick-on mailbox letters, metal house numbers, etc. Sometimes the red 6-foot long 5/16" dia driveway markers are set to one side along with some other items too long to fit inside the display. They are against the wall, which is good because it helps keep the straight. They cost less than $3 at one of the home centers, about $4 for the same rod at the other.
The displays I have seen also have the 5/16" rod in a shorter length. If you are set on 1/4" dia rod, there are usually driveway markers in the home centers' displays, the kind with the round reflectors on their tops, that have a 1/4" rod. They are obviously some kind of plastic, and I think it is fiberglass. They are usually significantly more flexible than the 5/16" dia rod.

Cycle-24.com (U.S. company owned by Hams) sells aluminum tubing specifically for the amateur (radio) antenna builder, will sell in small quantity, various diameters. Their smallest, 0.375-inch dia, 0.058" wall thickness 6063-T832 is currently offered for 50 cents a foot, only sold in 3' and 6' lengths. Their shipping charge is based on the cost of the order. $0 - $75 order, shipping is $20; $75.01 - $150, shipping is $25. There is no specific mention of anodizing, but they claim this is the same tubing used in commercial antennas.

I have no doubt a more optimal cut sheet could be devised, but it looks like it would take 5 6-foot lengths from cycle-24.com to have enough to make the narods and reflectors for a GH6n3, which would cost $35 to my door.

I'll take another shot at finding fiberglass rod at the local home depot.

Hi everybody

I need help with a GH that I optimized this antenna http://clients.teksavvy.com/~nickm/gh_n_U69V/gh6n3_9V6_13U4.html with the help of the member nikiml


I never built a antenna before, so i have some questions about this

In the active elements, the zigzag one... How I do the 90º corner.... Bending it or another idea ? The same applies to those narods

I read that the materials needed are copper and aluminium... both have to be hallow?

Any ideas or tips are appreciated, thank you...

Hi everybody


In the active elements, the zigzag one... How I do the 90º corner.... Bending it or another idea ?

I read that the materials needed are copper and aluminium... both have to be hallow?


I used bending because I used AWG10 copper wire. Being hallow (?) isn't a requirement by itself. It only makes the material lighter and cheaper, which is important when you want to climb a mast and put an antenna outside. I build mine and put it in the attic (which is a not so great idea for the quality of the signal) and I don't need it to be as solid as an external one (ie no bird will land on it).

I have seen people use copper pipes and solder them together or drill them and bold them together to make the 90 degrees.

jf

I'm in the process of making a GH. I'm using 1/4" copper tubing. The soft kind in a coil. For the 90* corners I used 5 or 6, 2" pieces of 14Guage copper wire bent to 90 degrees and inserted in each of the sections, then soldered. I was going to use 90* plumbing elbows but that would've gotten pricey.

Has anyone considered using the antennas from older cars, the ones that were made of telescoping metal tubes, for GH reflector rods? They were designed to withstand high winds when extended, lasted for decades, and do not weigh all that much. Only the first couple of tubes, the largest, would be needed to make up the needed lengths. The smaller tubes could be removed and discarded, and a gentle crimp or pop rivet should keep the tubes from sliding once installed on the antenna. I do not know if many of this kind of antenna can be found anymore, but they should be cheap. Think dark night, junk yard, hack saw.