You can wind your own 2.7mh chokes for KV4JT type solid state conversion projects. In order to solder the #40 wire I use a piece of sandpaper to remove the enamel (very carefully). I have not found a chemical that will dissolve the enamel. It is hard to sand without breaking the wire. Some types of wire have a low melt type of enamel that will allow you to solder it directly without any sanding or scraping.