you need about about 34 1/2 feet for the straight elements (for GH10n3). the tubing should do for that.

But it is probably not good for the bent elements.

Also - solid aluminum should be cheaper.

The solid rod was $6/lb, and the tube was $1/ft. I guess I'd have to run the math :) Maybe they'll give me a deal if I buy a crap load of it.

I also re-read a few posts and I see that the reflector rods can be as small as 1/4"...somehow in my head it was 1/2". Does the diameter matter for the reflectors? Or the bendy part for that matter?

The stuff rvsixer recommended looks like an easy solution to me having no tools to bend wire :)

to me having no tools to bend wire
You don't have an old board and an old nail ???

$6 a pound for scrap aluminum is a lot, considering they only pay you about 65 cents a pound for it when you take some in.
http://www.metalprices.com/

by my calculations 12 ft of 1/4" dia round solid aluminum would be aprox .7lb or ~ $4
which comes to ~33 cents per ft.
much cheaper.
and easier to bend...

The wide tubes are a great idea and build idea to simplify the design of the whiskers.

Idea - a little more complex, more work, not sure if worth the effort - but here it is:

1. Cut the tubes lengthwise in half, for most of their length, and then bend them open / spread them open at the correct angle - and make it a true whisker that way.

2. Cut the tubes into quarters, for most of their length, and then bend them open / spread them open at the correct angle - to approximate a 4-pronged "CONE". [ Now you're getting into real 3-D cone approximation ]


Cutting tubes accurately and straight lengthwise is not easy.

( I did a steel one, 1 inch thin steel electrical conduit tube, for about an 8 inch length, cut it in half lengthwise with a reciprocating saw / sawsall, and the tube in a vise - but not easy. Needed some half pieces to attach and get welded onto something else )

But if the tubes are thinner and softer material - like AL or CU - and if you use the right guide and the right cutting tool / cutting machine - I think you could do it well - straight and easy.

ex. Metal bandsaw with a jig to guide the tube straight and centered as you slide it lengthwise to do the cut(s).

ex. Table saw with thin blade. Again, need a cutting guide.

Careful - could be a dangerous procedure unless the workpiece is held and guided properly - and unless you have the right blade and machine and feed and speed to cut the tube safely, properly and efficiently. Machinists will know all about this sort of stuff.


In another thread I wanted to experiment with real 3-D CONES or approximations - but I don't have alot of time - a million other projects and responsibilities at the moment.

... and ... some mentioned that they think it would not lead to that much improvement.

Some mentioned, if you make 3-D cone approximations - you can make your whiskers shorter, and have the same performance - thereby saving space and material.

I imagined a multi-pronged whisker - which is what cutting the tube in four and spreading it would be.

Anyway - just an idea.

Good work with the 1" AL tubes.

FYI -- Aluminum Tubing is usually very readily available. Old Tent Posts as an example. Tomato steaks (green plastic coating).

Just a couple of weeks ago, we had our shingles replaced up in the attic (after 15 years), as well as the big heavy metal air vents in favour of the newer plastic models.

So just for kicks, I cut up two old aluminum red "mop" handles (into 4 - 21 inch pieces -- mounted on wood board (one and one-half inch spread) -- with baluns on each and fed into a splitter (in reverse).

I don't have to worry about the bowties hitting the roof and now I can get another 3 feet height (for my one TV).

Receive all T.O. and Buffalo stations. Fox 29 (in Mississauga is usually pretty tough for me), but not now -- up to 60 to 80 percent depending on tropo affect. 13-1 and 28.1 are iffy because of the angles and the reflectors that I use to point toward Buffalo.

Of course 9 and 11 are solid as anything -- maybe too strong for the tuner sometimes (98%).

These "mop" handles for anyone that wishes to have one are the common "red" ones available at most retail and dollar store outlets.

Sometimes, Freshco / Sobeys sells ones for a couple of dollars, where the blue mop-head has been torn off and is of no use to anyone.

Aluminum Shower Curtain Rods, purchaced at many hardware stores, are maybe around 5 or 6 feet long - if I remember correctly.

[ I can check - might be going to the hardware store later today for other stuff ]

They're definitely around one inch in diameter.

They're nice THIN aluminum material - probably very easy to work with.

5 ft = 60 inches, gives 8 tubes of only 7.5 inches

6 ft = 72 inches, gives 8 tubes of 9 inches

[ not counting any length lost for the cuts ]

[ but if you cut them with a tube cutter, you probably don't lose much length ]

so ... if you can get a 6 ft long AL Shower curtain rod - might be a good piece of material to use - for the do it yourselfer to build the TUBE elements.

Happy Building ! And Modelling !

This thread http://www.digitalhome.ca/forum/showthread.php?p=1419444#post1419444 touched briefly on the topic of metal and yagis. My assumption is that except for the driven element (the dipole), the metal used would not matter much since the elements are not meant to be connected together (non-metallic boom), so conductivity is not a factor. Is the assumption right? Would there be a performance improvement if all elements are made of copper versus stainless steel?

nezdepain, always stay with the same metal for elements, directors, reflectors, and attachments and you will have great results if the antenna design is good in the first place. If you use the Search This Thread tool for "Galvanic Corrosion" you will see great info on why mixing of metals should be avoided. For the best performance per cost most people are going with all aluminum construction these days. A non-conductive boom would mean using plastic or wood, but those are too weak to last long so metal should be used.

Thanks for the answer. The antenna is already built and is the attic. There is no issue of contact between two sorts of metal in this case. The driven element is made of copper and the parasitic elements are made of steal. I am just wondering "what if" all elements (parasitic and D.E) were of copper? In theory and practice, would it change anything on performance alone?

I am just wondering "what if" all elements (parasitic and D.E) were of copper? In theory and practice, would it change anything on performance alone?
A little, but maybe not enough of a difference to register on your TVs signal meter.

If you look closely at the picture of my 4 bay build with AL tubes, you'll see that the phase lines are tin plated at their contact points with the tubes to minimize oxidation or corrosion of the copper and the galvanic effect of copper/aluminum.
http://i1140.photobucket.com/albums/n574/BOUVAL-OTA/ChubbyM4zoom2.jpg

Nezdepain,
would it change anything on performance alone?
Not at all, leave it as is.
.

RE: The AL shower curtain rod. 1 " diameter (approx) thin AL tube.

[ For BOUVAL's 1" simplified TUBE whiskers. ]

I browsed around today ... and ...

The thin AL tube, shower curtain rod, seems to be - becomming - less and less common in the usual hardware stores. More rare now ?

They seem to stock a thin *STEEL* " Chrome Tube " instead - which looks like chrome steel instead. Chrome Steel is *NOT* so great for antenna elements.

[ and YA, real great in the shower too - it will eventually start to RUST and make a mess there in the shower eventually too - but that is the whole idea I guess - planned obsolesence - so you have to work, run, replace it, and go buy another one - $$$ more sales ]

Also - the Shower tubes seem to come more commonly in 5 ft (60 inch) lengths, rather than 6 ft (72 inch) lengths.

Not sure if price is that "good" either. A RONA store here in Ottawa East end wanted 30 bucks (!) for a 5 ft shower rod / aluminum tube. (the chrome steel ones cost alot less - obviously).

RETAIL SUCKS (sometimes).

In a different store, in a different section of the store ...

A HOME DEPOT had an 8 ft, 1 inch AL TUBE for around 15 bucks. Not a "shower curtain rod" - but could be used as one!
But that tube had thicker walls than the typical "shower curtain rod" - still good ...but maybe a little too good - thicker than necessary.
Good material - but a little pricey. 15 bucks not too bad considering the material.
It would still work quite well - and easy enough to work with - being AL.


Have a look in your local hardware stores - and see if you can find those 1" thin AL tube shower curtain rod tubes at a reasonable price. Or - for sure -save up ones that are scrap and thrown out - for sure.

Otherwise - if the prices "RETAIL" are too high, best to find a metal supplier with the right material you want, at a "reasonable" price - and get it there.


OR ... keep scavanging for scrap / at the curb / good / common materials and save them up until you have enough for your planned future builds.

Ha ha ... like me ... antenna material scavenger hunter

Start collecting those Aluminum lawn chair frames etc etc. cut out the straight AL tube sections with a tube cutter - and start stockpiling them.

[ Personally, I've got quite a stock of 3/16 or 1/4 steel rod from those lawnsigns - for yagi experimentation - but that's not the best material for a final build - might be ok for yagi director or reflectors - maybe NOT the D.E. driven element - and best then if GALVANIZED. ]

Maybe we could start a scrap antenna MATERIAL depot and trading co-op.

Cruise your "Used Building Material" stores. ex. Habitat for Humanity Re-Use it Centre

Also, I have noticed longer lengths of AL tube for sale in: Princess Auto Stores - not too bad price.

There's METAL SUPERMARKET stores too - not too bad - go have a look.
[ They had lots of various stuff there, and I got some 12 ft lengths of 1/4 AL rod there - not too bad pricewise - and good new material - but that rod is an AL alloy that is pretty STIFF and NOT so easy to BEND - I think it was T3032 alloy, something like that, not so easy to bend, good for straight rods, I wonder if there is a softer AL alloy that bends more easily - ex for GH ZIG ZAG elements or folded dipoles ? ]

Cruise the curb too.

Those are my suggestions.

Good Antenna building materials, at a reasonable price, are not so easy to find. - We're talking about - ALUMINUM rod or AL thin wall tube.

but that is the whole idea I guess - planned obsolesence - so you have to work, run, replace it, and go buy another one - $$$ more sales
The conspiracy theorist inside me agrees with you, heh. The prime example is the incandescent light bulb. In a firehouse in California, there is a light bulb that has been lit since 1909, over a hundred years. In 1924, the bulb makers got together and decreed that no light bulb should last over 2000 hours. The US congress, and pretty much all the other world governments did nothing to stop an unfair, illegal in most countries and immoral trade practice (re restraint of trade) in the ensuing years since. Think about it, 1 bulb should last us a lifetime.
The downside of course, is little to no employment for bulb makers and bulb shippers and bulb retailers, and we as consumers would in most cases be buying old stock. But I think those people, in that time period, would have been better off monetarily
as builders of radio/TV sets and shippers of radio/TV sets (which are heavier and more profitable for the shipper, heh) and retailers of radio/TV sets etc. If the governments would have followed their own laws that they made, we would have been better off overall.

Aluminum is a little different, you have to consider how its made. Aluminum is made by electrolysis, which requires massive electrical power to get aluminum from bauxite. (recycling to melt aluminum only requires 5% of that energy FYI) And since this US administration has limited energy growth, the price of aluminum has risen.
Actually, with Australia having massive bauxite reserves, I blame their socialistic government more for the increase in aluminum.

the chrome steel ones cost alot less - obviously).

RETAIL SUCKS (sometimes).

And if theyre thin, you cant tell the difference between those and aluminum, heh. Thats where naive consumers are sucked in. If they would only carry a magnet with them, like I do, they wouldnt be so naive.
More than ever, its buyer beware, especially with Chinese stuff.

Watch for old electric string trimmers (weed wacker). Most I've dissected have a ~ 3 foot piece of 1 inch aluminum tube.

Those large Shade Umbrellas.

Discarded Patio Table Shade Umbrellas.

My guess is that some have an inch and a half - 1-1/2" thin aluminum tube.

Carry your tube cutter with you.

Hello,

Say, I'm looking to build an M4 bowtie antenna and am trying to figure out the best materials to use and I'm looking to direct solder the balun to the phase lines. I've read somewhere that the CM 94444 is supposed to be pretty good as far as minimal signal loss, so I purchased 2 of them from a local distributor. I then contacted CM to find out what the lead wire is made of and at first they didn't want to tell me, but upon further inquiry, the reply I got was "I've been told it is aluminum coated copper".

I did a google search because I've never heard of that and wasn't able to come up with anybody selling or making aluminum coated copper... tin yes, but aluminum no. Any suggestions here? I'm trying to determine this so I can match the same material for the phase lines. If it is aluminum coating, then the issues come up about soldering aluminum, which apparently isn't an easy thing to do.

Do you think I got bad info from CM? The part is made in China and it's possible the guy just shot something back because he didn't know and didn't want to deal with it? The website shows two wire leads with the insullation stripped back, but the ones I got have loop connectors on the ends and they are a dull silvery color.

When I first called CM, the sales rep said they have been shipping a slightly different unit from the one shown on their website. Any help here would be appreciated. Thanks much!

MNStar Wrote"
I did a google search because I've never heard of that and wasn't able to come up with anybody selling or making aluminum coated copper

I hope this helps you. Here is the link about the Aluminum coated copper wire
they do make it.

http://www.tpt-wirebonder.com/en/applications/coated-wire-bonding/

MNStar,

I've seen over twenty different baluns in my life and the wires were always copper or tin plated copper.
.

David,M,B and BOUVAL,

Thanks for your replies. I clipped the loop connector off the CM Balun and it is a solid copper wire that is coated with a shiny silvery material. Not sure how to test what the coating is or if it even matters. I'm thinking that if I use copper phase lines, it would make sense to use very fine sand paper to remove the coating. Does that sound right?

I guess that narrows the material I will want to use for the phase lines and whiskers on the M4 I'm planning to build... copper or close to copper on the galvanic corrosion chart.

I contacted a welding supply shop nearby and they can get yellow bronze rods (which should be around 92% copper) or copper coated steel rods (1/8" diameter). I like the welding rod option because they are super straight. Maybe I'm overly anal, but I tried the drill method to straighten regular 8 gauge wire and it still had some wiggles, so I thought the welding rods would be better. I read previous threads about the coating material, but I didn't fully get it. Would a copper coated rod function just like a solid copper rod?

Do you think there is any noticeable gain using the super straight welding rods vs copper wire that is "almost straight"? If there really isn't any noticeable benefit, other than aesthetics, maybe I just need to get over myself and use the wire :p

If it really does make a difference, would it be best to use the welding rods made of copper coated steel or the yellow bronze welding rods or keep looking for regular copper rods from another source. I'm most concerned with getting the very best performance and it seems like each step, bend, connection, angle, distance, etc. will have a cumulative effect on the end results, so I'm just trying to put my best foot forward, so to speak.

Thanks much. I do need to say that I have been so impressed by all the knowledge shared on this forum. I'm pretty new, but am so glad to have found you all. Look forward to a great build and good fun along the way!