: Best Metals for Antennas: Performance, Soldering, Welding, Bending, Working
2011-04-03, 10:17 PM
Jeez I'm having a tough time bending this flashing into shape. The 10' x 10" roll I bought says .0092 on the page specs but I'm thinking this must be a lot thicker than what 2Bits used. It feels like coffee can thickness. I got it into the channel but as soon as I remove it the thing pops open a bit and its real tough to fold with my fingers. Very springy. Getting the edges closed is gonna be a chore.
2Bits do you have a link to the type of flashing you used? I see in one of the pictures its rolled out. Mine just recoils on itself.
Hi Javaman. The aluminum coil just says "N0.4605 Aluminum Flashing Coil". It does want to recoil on itself to an extent but responds well enough to a little flattening. I measured mine with an micrometer and it is .010" approx. The channel must be a tight fit and about 3/8" deep in order for it to form a tight "U" shape. Then you must run the forming tool down the length a few times on each side of the "U" to form it gradually into shape, pushing the metal over the steel round bar gradually. Remember that you must have the steel round bar inside the "U" to form it. I used a piece of wood with a 1/4" diameter groove filed into the end for my forming tool because wood slides very easily over the metal whereas a metal tool would bind and gall. Delrin or UHMW plastic would probably work even better but I had none handy. Ideally, a little roller with a groove cut into it (like a motor pulley for round belts) would probably work best. All in all, I must say that for me the metal seemed quite eager to form the way I wanted it and I finished all my tubes last week. Good luck!
2011-04-03, 10:24 PM
Nice job unclesam!
2011-04-04, 02:17 PM
I installed the 3/8" diameter aluminum reflector tubes using the method pictured in post #341 above.Wow great looking antenna. I'll be building a GH10n3 too and I plan on copying your great looking structure. The only difference is I'm using solid aluminum T6 throughout. I don't think I'll need the two wide holders for the elements, just having the six holders in the middle should be good for the solid bent element. I'm just a little concerned with having the reflectors being held at the ends since my reflectors will weigh considerably more and they may sag at the ends. Do you think it will be necessary to support them in the middle or ends or just having a longer middle supporting tube would hold up against the wind.
2011-04-04, 02:41 PM
I'm just a little concerned with having the reflectors being held at the ends since my reflectors will weigh considerably more and they may sag at the ends.
I dont think that relatively little weight difference with solid aluminum rods is going to make it sag.
2011-04-18, 11:19 PM
with respect to DIY yagis, what do you guys think of something like this?
Imagine a boom made from aluminum Conduit. Any ideas as to how ya could affix aluminum parasitic elements to something like a collar clamp?
If it could be done easily, ya could slide em on the boom, and lock down in place as per design distance along the boom. Having them like so might allow for optimising? I think they come in packages of like 10 or 20 per package for 5 to 10 bux a package, depending where ya get em.
aluminum collar clamp (http://www.google.com/products/catalog?hl=en&sugexp=ldymls&xhr=t&q=5/8%22+aluminum+collar+clamp&cp=26&qe=NS84IiBhbHVtaW51bSBjb2xsYXIgY2xhbXA&qesig=eezhRN4NxVKQBVMUFkD9wg&pkc=AFgZ2tnADsVX1Z17Fa1j7nQo48TagW0UNZf9pjOny0nQh9y9walXUYlE tEgOwjWmwoKH5ePLW3bzWp11YJkaFc4kv_0L34MC2A&bav=on.2,or.r_gc.r_pw.&um=1&ie=UTF-8&cid=13903148616539739287&sa=X&ei=JvCsTfWwMNG_gQe6oMmHDA&sqi=2&ved=0CD8Q8wIwAw#)
2011-05-27, 11:50 AM
I found some galvanize 9 gauge wire in a spool at my local Lowes store. That's the biggest solid wire I could find. Would this be a good choice to make a GH with? Thanks.
2011-05-27, 12:25 PM
You'll want active elements to be of aluminum or copper. For reflector use you'd be okay with that galvanized steel wire in some sort of mesh, but for that purpose it would be easier to go with the 2x3" corn crib mesh sold at Lowes and other stores.
See the chart in Post #8 (http://www.digitalhome.ca/forum/showpost.php?p=772043&postcount=8) for a comparison of electrical conductivity. Galvanized steel isn't even on that chart, but it is below stainless steel... ;)
2011-05-27, 03:06 PM
Thanks for that information. Looks like I'll be returning it shortly.
2011-06-09, 04:39 PM
I have just about finished the plastic frame for my second single-spine GH10n3 (the spine does not get drilled) and am still wrestling with concepts for the reflector rods. The rods will be prepared as separate assemblies and will just pop into the frame, so I can use any kind of rod. I have toyed with wrapping 1/4-inch fiberglass rods (driveway markers from home center) with foil or foil tape, but I worry about durability. I was wondering if it would work, electrically, to wrap aluminum window screen around the fiberglass rods. Window screen is cheap, lightweight, is durable outdoors, would be easy to wrap around the rods, and I have a roll of it. It simplifies construction to make each reflector (pair of rods) out of one continuous fiberglass rod, and I have developed an elegant way to grip the rod and attach it to the antenna frame. I just need to work out the metallic covering.
2011-06-09, 09:07 PM
I was wondering if it would work, electrically, to wrap aluminum window screen around the fiberglass rods.
Yes, it would work electrically. But how are you going to keep it tight around the fiberglass rod ?
2011-06-09, 11:14 PM
Wouldn't be easier and cleaner to use aluminum foil tape? Do you foresee problems with it?
2011-06-10, 10:49 AM
I have a couple ideas for keeping the screen wire tight around the rod, thought I had better find out if it would would work electrically before trying experiments. One way would be to cut a long strip of screen, fold over the cut edges to make them neat, the strip cut wide enough that the edges came together as a lengthwise seam along the bottom of the rod. Lace the two edges together using a long wire taken from the screen material. The interior end of the wire cylinder would be clamped by the mechanism that grips the rod to the antenna frame, and the loose end would be covered by a rubber cap.
2011-06-10, 10:58 AM
I have worked out a way that should get the foil tape neatly onto the fiberglass rod. I had just about settled on the foil tape method when a discouraging image came to mind: birds' claws. I am disinclined to provide a bird perch atop the antenna, but I may go with the foil tape anyway, just to see how it works out. The frame I am building will allow for the reflector rods to be removed, if they become damaged, and replaced fairly easily with some other design. I would prefer to use quarter-inch aluminum tubes, but I have yet to find a reasonable source.
2011-06-11, 10:45 AM
Another approach to making GH 10n3 reflectors from 1/4" dia fiberglass rod (home center driveway markers) would be to wrap the rod with sheet aluminum flashing material. This should be eaiser than covering the rod with metal window screen material, and the flashing is not as susceptible to damage as foil tape might be. I do not think I could make quality, self-supporting reflector rods by the clever method of shaping flashing into 1/4" dia tubes. However, I think I could roll it around the fiberglass rod. The fiberglass rod could extend through all of the length of each metal tube or just part of it. That way, each reflector (pair of tubes) could have a single attachment to the antenna's plastic frame. Attaching each pair as a single length of fiberglass rod would be easier than attaching two thinwall hollow metal tubes separately.
2011-06-11, 11:26 AM
to wrap the rod with sheet aluminum flashing material
Someone else on this forum was doing that, but with 3/8" or 1/2" diameters. He made up a jig with a slot in the dowel to start the wrapping. IIRC, he used pop rivets to hold the tubes together.
Rolling the flashing up inside of another tube is another idea.
Copper flashing would be nice, as the seams could be soldered. But its pricey.
1/4" dia fiberglass rod (home center driveway markers)
Fiberglass electric fence posts from Tractor Supply are even cheaper at $1.29 each. They are 3/8" in diameter and solid, therefore a bit heavier.
2011-06-11, 09:12 PM
Sounds like alot of work and expence for reflector rods . Is 1/4" solid aluminum rod that expensive in the states ? I pay .33 cents / ft . for it here in Ontario .
2011-06-11, 11:57 PM
It kind of is here, with no Metal Supermarket or something like it. At Lowes, Home Depot and ACE Hardware, it works out to like around a $1 a foot or more, for the 3 to 6 ft pieces they sell. But 6 gauge solid copper wire is only 32 cents a ft for me. :)
2011-06-12, 12:46 AM
I see now , lack of good suppliers . Have you tried going to a local welding shop ? Thats what I ended up doing after Metal Supermarket up`d the price everytime I walked in , and it was cheaper aswell .
2011-06-12, 06:07 AM
Thats not a bad idea, Ill have to look for a shop that does heli-arc welding. The local place I use for welding repairs only does iron/steel and has no metal inventory, but he's cheap, heh.
Scrap yards are also a good source. Unfortunately, I have no local scrap yard anymore. The nearest remaining ones are 40 and 60 miles away. The general rule at scrap yards (for little buyers) is that they will sell you the metal for twice what they will buy it from you. So now, that would mean I would pay about $1.20 a pound. That would work out to about 4 - 5 ft of 1/4" aluminum rod ?
2011-06-12, 01:12 PM
I was perfectly happy with the 3/8" reflector rods, scavenged from old commercial antennas, I used on my SBGH6 and first 10n3, but I have run out of them. If I wanted to use 3/8" tubes again, I would not be above buying a new antenna and using its tubes. However, the GH10n3 I am currently building is intended to be minimal and lightweight, so I am trying to go with 1/4" reflectors if I can. I do not believe this design will support reflectors made from solid aluminum rod.
Methods offered in this thread for rolling your own seem to me to be difficult at the 1/4" size. I found an excerpt on the Internet from a machinist's manual that told how to make tubes from flat stock by drawing it through a succession of smaller and smaller holes. I drilled holes in a stick of wood, the smallest 1/4" with a countersink on the entrance side. I cut a strip of thin aluminum flashing, cut the leading end into a long taper. I pre-rolled the strip over a 3/8" dowel using my fingers, and hammered the tip of the taper around the taper of a center punch. I pulled the strip successively through the holes using a pair of pliers, which required almost no effort. If the tube came out curved, I put it through the hole again, pulling at an angle to counteract the curve. I straightened the final tubes by rolling between a board and workbench top. Those shown are the first I made, and the results are promising. The tubes really are stiffer than I expected. Some effort in shaping the entry to the draw holes would probably improve the quality of the tubes, and I suspect this method is used to produce tubes for commercial antennas.
Also in the photo is my first effort to wrap thin aluminum flashing around a fiberglass driveway marker rod, which I have referred to as being 1/4" but which actually measures 5/16" and is solid. This rod is significantly stiffer than the other markers sold in home centers, such as have round reflectors on their tops, which do measure 1/4". I pre-curved the strip of aluminum flashing around a dowel using my fingers, then smoothed it by rubbing it lengthwise with the wheel taken from a small pulley block. I repeated the process using a 1/4" metal rod, then forced the resultant tube over the fiberglass rod, which was a very tight fit. A refinement of this method should produce a durable thinwall metal reflector (two tubes) that can be supported and attached to the antenna as a single fiberglass rod.
The ideal might be to insert the fiberglass rod into the tube drawing process, to have the rod come out clad by just pulling it through with the aluminum strip. The inner end of each tube would be clamped in place by the mechanism that clamps the rod to the antenna frame, and the outer end could be covered by a rubber tip. Otherwise, the rod and one side of the aluminum could be given a very thin coat of contact cement, which is waterproof, to bond the tube to the rod.
I found a source of small-quantity 1/4" O.D. 6061 T6 Al tube, .035" wall thickness, airpartsinc.com, supplier to aircraft builders and hobbyists. They sell in 6' increments, will ship up to 6' by UPS, will chop up the 6' sections into shorter pieces. They do not mention anodizing, but claim that the tube is protected by an "accelerated aging" process. Cost is $1.50 a foot, and the website does not calculate shipping cost. You can call in advance to find out what would be the actual shipping cost.