Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Under the #90 is much like the B30 - just smaller and a center screw with an iron plate smashing the heater to the tank.  Which having that center makes it fun, not.  So from my photo you see there are two smaller strips of mica wrapped with the Nichrome.  So those heater strips straddle the center screw.

Since I didn't do a lot of thinking, I went straight to heater cartridges and I modified the iron plate on the power lead side.  This might have really screwed me over trying to go back to a mica heater.... but live and learn.  This #90 is all just me learning anyways but hindsight I'd have done things differently.  So I wouldn't knock your overthinking at all! ;-)