Copper clad aluminum wire

[multieagle]

Has there been any discussion re use of copper clad aluminum wire for coil construction? I note that it is excellent for HF applications, but not so good for DC.

Copper clad aluminum wire.

CCA Used for HF Applications

One of the main traditional applications of CCA is in communication cables as the central conductor of coaxial cables. CCA is also sometimes used in enameled magnet wire when low weight is critical (e.g. coils for headphones and aircraft instruments). Due to the skin effect, which means that high frequency signals are mainly transmitted in the surface layers of a conductor, CCA is usually used for carrying high frequency signals. For these applications (e.g. coaxial cable) the higher DC resistance of the aluminum core is not so important. Indeed, in really high capacity, very high frequency coaxial cables signal transmission within the central core of the conductor is so negligible that hollow copper tubes, not solid wires, may be used.

[bbsailor]

Has there been any discussion re use of copper clad aluminum wire for coil construction? I note that it is excellent for HF applications, but not so good for DC.

Copper clad aluminum wire.

One of the main traditional applications of CCA is in communication cables as the central conductor of coaxial cables. CCA is also sometimes used in enameled magnet wire when low weight is critical (e.g. coils for headphones and aircraft instruments). Due to the skin effect, which means that high frequency signals are mainly transmitted in the surface layers of a conductor, CCA is usually used for carrying high frequency signals. For these applications (e.g. coaxial cable) the higher DC resistance of the aluminum core is not so important. Indeed, in really high capacity, very high frequency coaxial cables signal transmission within the central core of the conductor is so negligible that hollow copper tubes, not solid wires, may be used.

multieagle,

Consider that eddy currents could be developed in the aluminum wire itself. That is why tin plated stranded wire is used to help breakup eddy currents and why thin strand (AWG32) Litz wire is used at very low delay PI detectors seeking very small targets.

bbsailor

[multieagle]

Thank you. I had a 50' length of CAT6 500Mhz UTP CCA Ethernet cable (24AWG) not being used for anything else and was hoping to pull the stranded wire out of that for the Surf PI project.

Gord

[mickstv]

I've been using CAT5 single strand for a few of my coils. It seems to be ok and can get sub 10us samples using it.

[multieagle]

What I have is 4 pair double stranded:
Copper Clad Aluminum (CCA)

Stranded 568B wire

4 Pair twisted Wires

Unshielded

24AWG (.5mm)

[Davor]

I helped rewiring a few old houses with old aluminium electrical wiring. If you are remotely able to picture an electrician's nightnare ... this is even worse. There was a period when in the former Yugoslavia you couldn't obtain copper for house wiring, so many houses built in that period have aluminium instead. Beside the obvious mechanical disadvantages the aluminium in contact with copper develops some nasty galvanic chemistry that destroys such contacts and leads to rather spooky effects. t takes a year or so for the joint to start deteriorating in dry conditions.

The only thing that I've seen even worse than aluminium wiring is "protecting" copper joints with silicone. These work fine for a week or so.

[golfnut]

The point missed with Litz vs stranded is... Litz strands are electrically isolated from each other along their length with enamel insulation - Strands are only joined together at each end.

With Stranded, they are bare and so all electrically bundled together along the length. Not the same.


A win with Litz, which doent surface on here much, is the fact that the self inductance per unit length of Litz is low. This is because all of the wires are all in parallel.
(rem.. equal Parallel inductors half the L, lots of L's in Parallel - really low L)

This is one of the reasons its good in fast Pi's - along with skin, proximity, low eddy support.

Its hard to make, relative to magnet wire, and thats why its not cheap.

S

[golfnut]

Square copper

Has anyone used square copper wire - in order to get the turns closer and packed with a better stack less airgaps etc to get the efficiency up.

Anyone seen it in 0.1, 0.2, 0.3, 0.4, 0.5mm ??


S

[multieagle]

This is interesting! We also had here in Canada houses constructed with aluminum wiring. It was outlawed in the 1970s. I had thought the problem was with heavy voltage, but now see that once exposed to air, aluminum begins to oxidize. So, why take the risks?

Okay, that is solved. Thank you.

Now, one other newbie question. Have found: Vectorbord W28-6EV "buss wire" which is tin clad copper. It is 28AWG, single strand, white Teflon insulated. Any thoughts on that?

[multieagle]

Ref square wire. Have seen it on eBay as "jeweler's wrapping wire" in various lengths. Some described as "half-hard", or "non-tarnish, pro-quality", in various lengths 14-22ga. Of course most all bare wire, but some with clear anti-tarnish finish. Guess you could spray it with some manner of insulation.

I note there is a flat insulated copper wire: http://www.hmwire.com/flatmagnet.html 11-30awg. Wonder if that would work in a flat coil? Ha, ha . . . would take some mighty delicate wrapping!!!

[Davor]

Look for wires that are used for their conductivity. It means annealed copper. It can also be tin clad, as it won't make difference. Jeweller's and every other hardened material is made for other purposes and conductivity will suffer.

Copper is annealed for one reason: to regain conductivity. As such it will have superior conductivity to any alloy. IMHO copper is far superior as a choice of material for electronics and RF to silver, simply because you'll hardly ever get hold of pure annealed silver, and even then it will make only a negligible difference. Sterling silver is far worse than copper.

[Jerry]

This is interesting! We also had here in Canada houses constructed with aluminum wiring. It was outlawed in the 1970s. I had thought the problem was with heavy voltage, but now see that once exposed to air, aluminum begins to oxidize. So, why take the risks?

I think the problem had much to do with making connections. Aluminum is so soft it is difficult to make/keep a good tight connection. I suspect that would be the main problem with others uses as well.

Jerry

[Skippy]

Only pure silver is a better conductor than pure copper. As mentioned, Sterling silver (92.5%) has a conductivity of 85% of copper's value. Pure silver is 105 - 108% (depends on purity etc). This UK wire supplier has some interesting stock, including square/rectangular ECW, and enamelled fine (pure) silver wire, should you have the need. http://www.wires.co.uk