There is a kit version. Sort of.
the kit version is very nice as they can use the tokin transistors from japan.
Those transistors are actual V-fets, from the last batches of high current RF use design criteria.
Tokin used the original process for making V-fets, IIRC. Japanese made and in the last run of Japanese V-Fets.
I’d have to check, but I suspect the Tokin transistors have a better spec than the First Watt SIT transistors. As in higher frequency capacity, greater current capacity and possibly more linear. Or at least individually tested and quality spec’ed, sorted and QT’d for release to the public (like all high end expensive transistors).
To clarify, the SIT transistor that Nelson had made up, came from an offer to do so, from Semi-south, a smaller transistor manufacturer. Nelson had the proto batch made up, and then Semi-south was bought up by another manufacturer. The end...( of that ride). The Tokin, is another matter. It came from a decades long run of making the best in V-fets for extremely demanding applications of extreme voltage swing and extreme current loading (think radar power amplifier). That run had a chance to be perfected over decades of iteration.
Thus, a Tokin version, might be capable of having a higher voltage and higher current rail, for a notably higher wattage and impedance handling range than the SIT-3.
The operative word being ’might’.
Importantly, the (very) few who’ve had the chance to make the comparison say the Tokin version outperforms (according to them) the SIT-3.
Last chance.....
