ZachTek WSPR TX Mini Build Instruction page 10

Now use a knife to scrape of the burnt isolation until the ends are shiny all around.
Finally tin the ends with the soldering iron and some solder.
If you have done a good job getting the enamel off it should take solder easily, if not scrape some more with
the knife and pre-tin again.
It is important to get the enamel off or else the coil might not make god contact when soldered in to the board
and as a result, you might not get a signal trough your filter.
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