Alternative primary coil materials
Kizmo, Wed Oct 31 2007, 08:50AMAlmost everyone are using copper tubing as primary coil. Aluminum wire/tube works well too, as discussed earlier http://4hv.org/e107_plugins/forum/forum_viewtopic.php?7306.post.
But is there any other materials, for example steel cable? It is a lot cheaper than copper, 12mm steel cable was 1.20e/m at local hardware store.
EDIT: Found it at last. As i suspected steel has quite poor skin depth compared aluminum -> not good.
At least it would be good for toroid like this one: http://4hv.org/e107_files/public/1193502301_123_FT27432_27102007001.jpg
Re: Alternative primary coil materials
Dr. Slack, Thu Nov 01 2007, 08:34AM
The reason that everybody uses copper is that, of the materials that are good electrically, Silver, Copper, Aluminium, Gold, there are outlets in every town of every country that will sell you 10m of any diameter of copper for not all that much money, which doesn't even hold for alluminium. The same goes for what you are most likely to pull out of a skip (dumpster). There's no reason (apart from looks), why you should not use multiple thin copper wires twisted together, maybe 1mm/2.5mm cores salvaged from wiring. Being bare, it won't give you the full Litz wire advantage, but it will be as good as the same surface area of tube, and cheaper.
Actually the Q of the primary is not a mega-problem (compared to the streamers, spark-gap etc), so almost any conductive and non-ferrous material would also do at a pinch, brass, zinc, but see the comments about availablity above.
Once you go ferrous, iron, steel (stainless steel would be quite a challenge), the primary RF resistance does dominate the performance.
Dr. Slack, Thu Nov 01 2007, 08:34AM
The reason that everybody uses copper is that, of the materials that are good electrically, Silver, Copper, Aluminium, Gold, there are outlets in every town of every country that will sell you 10m of any diameter of copper for not all that much money, which doesn't even hold for alluminium. The same goes for what you are most likely to pull out of a skip (dumpster). There's no reason (apart from looks), why you should not use multiple thin copper wires twisted together, maybe 1mm/2.5mm cores salvaged from wiring. Being bare, it won't give you the full Litz wire advantage, but it will be as good as the same surface area of tube, and cheaper.
Actually the Q of the primary is not a mega-problem (compared to the streamers, spark-gap etc), so almost any conductive and non-ferrous material would also do at a pinch, brass, zinc, but see the comments about availablity above.
Once you go ferrous, iron, steel (stainless steel would be quite a challenge), the primary RF resistance does dominate the performance.
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