Film-Tech Forum ARCHIVE: Bare aluminum wire

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Posted by Josh Jones (Member # 447) on 08-07-2002, 02:10 PM:

Does anyone know where to get this stuff? i need about 25 feet of 10 awg for an antenna project.

Josh

Posted by John Pytlak (Member # 331) on 08-07-2002, 02:19 PM:

Some links:
http://www.jchwire.com/jchwire/Contents2.htm
http://www.sciplus.com/category.cfm?subsection=11&category=112
http://www.erico.com/erico_public/pdf/fep/strike/S256C2_1.pdf

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Paul G. Thompson (Member # 655) on 08-07-2002, 03:23 PM:

I have a stupid question:

Why aluminum? What's wrong with copper?

Posted by Josh Jones (Member # 447) on 08-07-2002, 03:31 PM:

it's a J-pole antenna. Because it radiates omnidirectionally, the supports cant be metal, only wood. copper would also corrode and foul up the tuning slider in the rain and is heavier than aluminum.

Josh

Posted by Jeff Stricker (Member # 224) on 08-07-2002, 04:09 PM:

Josh, If your J-pole is for the 120 MHz or higher make it from 1/2 in copper water pipe and elbows. Cut pieces to length and solder together. Many many of these have been made for the 2 m amateur band.

Posted by Paul G. Thompson (Member # 655) on 08-07-2002, 08:18 PM:

Oh.

Posted by Josh Jones (Member # 447) on 08-07-2002, 11:02 PM:

Its for the FM band. I want to do some low power FM experiments and the design I have exhibits 8.8 db of gain! Havent had much luck yet, all the places in town stock service entrance cable, but it is stranded and also insulated.

Josh

Posted by Phil Hill (Member # 371) on 08-08-2002, 12:30 AM:

At those frequencies you may be better off with aluminium tubing rather than 10 AWG solid wire due to "skin effect". The tubing may also be easier to "assemble" especially if in some sort of co-linear radiator/array.

FYI...aluminium oxidizes much more and much faster than copper, especially if in contact with dissimilar metals and/or in a damp environment.

I've used 3/8" rigid copper tubing with a copper ground-rod strap type clamp for slide-tuning on 2 meters before.

Keep in mind wood makes a great conductor when wet.

You may be able to find 10 AWG solid wire sold locally for use as lightning-rod ground wire, clothes line, or perhaps "guy" wire.

>>> Phil

Posted by Paul G. Thompson (Member # 655) on 08-08-2002, 01:14 AM:

I talked with Josh, and he referred me to a website about the design of what he wants to build. Now I see why he needs AWG 10 aluminum wire. I'll try to get some for him, as nobody in his are stocks that stuff.

Phil, I knew I saw that type of wire recently, but I could not remember where. Yes, it was also used as clothes lines. Then, another light bulb lit. We were also using it as grounding wire for the satellite dish support frames at the radio station. I agree with you on the corrosion factor. But it is light weight, so that might be the advantage.

Josh, check out the hardware stores. Also, get ahold of Lance - he might have some of that stuff laying around if he used it for the same purpose as we did.

We might be able to get it from broadcast suppliers, too.

**********************************************************************
Just as general information, aluminum wire has a "memory" - that is, when you bend it, over a period of time it will have a tendency to return to its orginal shape. I understand that is one of the chief causes of electrical fires in the older homes (especially mobile) that used aluminum wire in electrical applications. It has the tendency to pull itself away from the connectors in the push-in devices such as switches and recepticals used today. For those who live in these types of dwellings, it would probably be a very good idea to use the screw terminals when you change them out. I believe aluminum wiring in homes (mobile or stick-houses) was outlawed around 1970. (or at least in that time frame)

While you are at it, check your aluminum wire terminations in your power panels for tightness and signs of overheating at least once a year. Also, remember that when you secure an aluminum wire to a copper device in electrical applications, a special chemical is needed to prevent oxidation caused by the "Battery Effect." The green slimy stuff you see around and in the service wire connections of the power panel is that compound I am addressing. DO NOT clean it from the terminals. That stuff didn't grow in there, and it didn't come from Mars.

However, if it looks like corrosion, it probably is. Be careful how you determine what it is. De-Ox feels like grease.

Corrosion feels and looks like corrosion. If it is corrosion, immediate action to correct it is required.

Failure to use this compound could result in a very dangerous situation for you and your family.

This compound can be obtained from hardware stores. One of the brand names is De-Ox. It is dark green in color. Most electrical contractors I personally know use that specific brand.

Remember....aluminum wire for service entrance is still being used today. It is in your main feeds coming into your home or business. Once again, I say check those connections (or at least have them checked by your electrician) in your power panels at least once a year. I do. I headed off a potential electrical fire in one of our theatres by checking that once a year.

When it comes to electrical safety, there can be NO compromise.

OK, I babbled enough on this subject. You do as you wish.
**********************************************************************

Paul

Posted by John Anastasio (Member # 607) on 08-08-2002, 06:09 AM:

Josh, the stuff you're looking for is available from Antique Electronic Supply (http://www.tubesandmore.com) as Aluminum Bus Bar wire. It was used in battery radios from the 1920s as the main wiring component in the chassis. I have a roll of it laying around somwhere and I'll send it to you if you like. Just e-mail the address.

Posted by Gerard S. Cohen (Member # 994) on 08-08-2002, 10:00 AM:

Paul;

That safety information on aluminum power wire installations you posted is valuable. I didn't know of the existence of De-Ox compounds.

Aluminum power wire is not permitted in the five counties of New York City. Nor is Romex. Power installations require a minimum of flexible metal shielded wire (BX cable), or where exposed, as in basements, tubular shielding.

Gerard

Posted by Ken Layton (Member # 133) on 08-08-2002, 10:24 AM:

Radio Shack # 15-035 (40 feet) for only $4.99

It also can be used if you lock yourself out of the car.

Posted by Josh Jones (Member # 447) on 08-08-2002, 10:58 AM:

John, Ken, what gauge is it?

Josh

Posted by John Anastasio (Member # 607) on 08-08-2002, 11:40 AM:

It's #10AWG aluminum....and now that I'm looking at it, I remember where it came from. It's the grounding wire supplied with my DSS satellite dish. Ken's right...it's available at Radio Shack. I think it comes in 50-ft lengths. I hope you'll post a picture of your antenna creation when it's done. With that kind of gain, it must be a co-phased array of some sort.

Posted by Josh Jones (Member # 447) on 08-08-2002, 03:26 PM:

Here is a link to the proposed antenna. There are two picture at the bottom showing it after it was hoisted into the air.

Josh

Posted by Phil Hill (Member # 371) on 08-08-2002, 04:48 PM:

It's good to finally see what we were all talking about...

Hey Paul, it sorta reminds me of the old ham radio "halo" type antenna series like the "Saturn 6". Ummmmm, but that was made of alumium tubing and tuned with big ol' capacitor plates in the "ring". Had a killer gain and pattern...even more when stacked as an array.

Also, while it is very important to make sure all high-power connections are tight, I would be *extremely* careful about tightening the service feed to any main panel, sub-panel, or meter panel. It's wise to call an electrician if not familiar with these deadly live circuits that in many cases must be serviced while engergized.

There are anti-corrosive pastes made specifically for antenna use that can be found at ham radio suppy stores.

I still would be concerned about the wood. It would suck-up the RF radiated power by absorbtion depending on length and especially when wet....even if coated.

>>> Phil

Posted by John Anastasio (Member # 607) on 08-08-2002, 09:44 PM:

These antennae are popular with the FM "Pirate Radio" folks because they demonstrate a high gain in the lateral direction and almost no sky wave. They're also easy to stick up and pull down real fast to avoid the authorities. The design is not unlike commercial transmitting antennas used by FM stations. I have a two-bay circular dipole that looks a lot like this one at the transmitter site I manage, only it's 450 feet in the air and made out of stainless steel pipe. If you're planning to do a little guerilla broadcasting, be warned; it's easy to exceed the legal limits with this antenna, even if you're using a transmitter operating with a legal output power.

Posted by Paul G. Thompson (Member # 655) on 08-09-2002, 04:33 AM:

Phil said:

**********************************************************************
Also, while it is very important to make sure all high-power connections are tight, I would be *extremely* careful about tightening the service feed to any main panel, sub-panel, or meter panel. It's wise to call an electrician if not familiar with these deadly live circuits that in many cases must be serviced while engergized.
*********************************************************************
Phil, Absolutely! That's why I mentioned something about "Or at least have them checked by your electrician..."

Thanks for bringing that up again. I didn't put enough emphasis on that statement.

Posted by John Pytlak (Member # 331) on 08-09-2002, 07:51 AM:

How effective would this antenna design be for use with a RECEIVER? Specifically, for use with a scanner in the aircraft band (118 to 136 MHz)? Would vertical/horizontal polarization of the signal be an issue? I live about 10 miles from the Rochester airport, and would like to use a gain antenna to get clearer reception of the tower and aircraft on the ground, while having an omnidirectional pattern for airborne planes.

Would this be a good design to use as an omnidirectional antenna with an FM stereo receiver?

Posted by John Anastasio (Member # 607) on 08-09-2002, 08:36 AM:

It would only be an excellent antenna for the one frequency for which it is tuned. It would indeed be an omnidirectional antenna. Your best bet for an antenna that you want to pick up a specific source with like the local airport tower would be directional one that exhibits high gain in one direction only, like a Yagi, parabolic or corner reflector that you could point right at the airport's antenna system. If you want to pick up the aircraft in the sky as well, they're coming from a higher reception angle. I'd say that your best bet would be a vertical antenna with a good ground plane tuned to the tower frequency....then you'll get everything. The best way to get airports is to get your antenna well-tuned and up as high as you can.

Posted by John Pytlak (Member # 331) on 08-09-2002, 09:00 AM:

John:

Thanks. I've already got a vertical antenna with ground plane, but I probably should remount it higher than the 20 feet it is now at, especially since there is a hill that obstructs "line of sight" between my house and the airport. Shouldn't I tune it for the middle of the band (127 MHz.), rather than the ROC tower frequency (118.3 MHz)?

Any hints on getting the ground side of the conversations for the regional (CLEVELAND, TORONTO) Air Traffic Control (other than going up in an airplane or building a mile-high antenna tower)? Is there a listing of where the regional ATC transmitters are located, so I could aim a high gain directional antenna at them?

Posted by John Anastasio (Member # 607) on 08-09-2002, 09:24 AM:

Absolutely right. If you want to get all the ATC frequencies, it should be tuned to the center of the range. The information about the antenna sites is available from the FAA, but they may be a bit wary these days. You can glean tons of info for about six bucks by going to your local flight school and buying the "sectional" chart that pilots use for navigation. I think that Toronto shows up on the Lake Huron sectional chart. These charts show not only the airports, but all the frequencies for ground control, ATC, VOR, ATIS, field elevation,locations, etc. The problem with these is that they're aimed at (you guessed it) AIRPLANES, up in the sky, not antennas down on the ground. Some large airports now have their towers available for listening via RealAudio. The holding pattern for Newark International is right over Yardley, PA so there's always something to hear at my house in Trenton ( you can actually watch them circle) , but I can't get the tower from here.