4 Metres 1 X 0.7mm Solid Core Connection and Coil Wire



Solid core wire is used as it plugs into the breadboard more easily than stranded wire.  Enameled copper wire is more normally used for winding the coils, but the insulated copper wire is easier to handle if there is room in the design, and the electrical results are equally good.  The colour of the insulation may differ.  About three metres is used to wind the two radio coils and 1 metre for the other interconnections to the speaker, variable capacitor, and to make the wire jumpers used on the breadboard.

This is tinned copper wire.  It is copper wire with a thin coating of tin which prevents slow oxidation of the copper underneath.  Purists might prefer to use untinned copper wire for coil winding.  High frequency radio alternating currents tend to flow mostly along the outside of the wire due to a phenomenon called skin effect.  Tin has a higher resistivity than copper, so it could be argued that we're effectively adding resistance and loss to the radio signals by using tinned wire.  This would cause the quality factor Q in the coil to drop, resulting in lower sensitivity and broader tuning.  In practice, I've not been able to detect any difference in the performance in this radio.

Finding untinned equipment hookup wire like this is quite hard, usually involving several rounds of email questions and a test purchase from a given supplier.  After which, they will send you ten reels of the tinned stuff and somehow expect you to like it.

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