Don't worry about spamming "my" work. First of all, i am not the original designer of the system used. Standing of the shoulders of others, as they say. Secondly, i very much welcome discussion of what improvements could be done to the little, simple circuit i made. And finally, since i am not an RF guy myself, i very much welcome any discussion about that stuff.
Personally? Yes, i am pretty sure that in (at least) this instance there is not much (if any) gain in using litz wire, compared to solid core wire. As said, any heatup that i could note was pretty much only in the cores themselves. This is most obvious with the transformer on the ferrite core. Simply using a bigger core got rid of most of the heat, while still using solid core wire. This is proof positive that the core itself has much more influence than the type of wire used.
Plus, most of the manufacturers of radios out there use solid core wire as well. Yea, some might say they are all wrong, but i highly doubt it. Theory is one thing, practice is another. Sure, you may get rid of a small amount of losses by using litz wire, but the cost of doing so is probably much higher than the cost of the actual losses. After all, companies are not charities. If they could make something that gives them an advantage over their competitiors, they will do it. But since rarely anyone uses litz wire in such applications, i have to assume that the cost/benefit ratio is heavily tilted towards simple solid core wire here.
But hey, that is just what i think. Build it using litz wire, and let's see how it compares. I'm always open to that kind of stuff. But you have to show me substantial data to change my mind. So, unless someone builds the circuit as is, plus another one using litz wire, and then compares them and finds substantial benefits for litz wire, i will stick to my preliminary conclusion that the type of wire simply does not matter that much, if at all.
Greetings,
Chris
Edit: To make it clear: I really mean same circuit. That is, same parts, same layout, everything the same, except for the inductors and transformer in the RF path. Then show what the actual differences are. Does it heat up half a second faster due to less losses? Does it consume a few miliamperes less current to achive the same output on the same tip cartridge? If so, what is the price difference between that litz wire and solid core? Solid core is bog standard and cheap. Litz wire, not so much. At least for RF applications. There is no gain in saving one buck in electricity during the lifetime of the thing, when using litz wire costs 2 bucks more... Heck, even if i save one buck and the litz wire costs me one buck extra, i have saved nothing at all.
Keep in mind that this project is meant to be built by others without resorting to too many exotic parts. The FET driver is already quite exotic, but still readily available. Some specific litz wire is (in my experience) much harder to come by, compared to regular magnet wire....