Gas, electric, induction
The pot and the hob
The moka pot was made for gas, but it gets along with most hobs if you learn how each one gives and keeps its heat.
Gas
The easiest hob for a moka pot: you see the heat, and it changes instantly. Use the smallest burner that is stable and keep the flame under the base, never curling up the sides, where it scorches the handle and overheats the coffee.
Small pots wobble on wide grates. A small ring that sits on the grate, or a flat diffuser plate, keeps them steady.
Electric plates
Coil and solid plates keep their heat after they are switched off, so the trick is to move the pot, not the dial. Use a plate about the size of the base on a medium setting and lift the pot away as soon as it gurgles.
Glass-ceramic
The same idea as electric plates: medium heat, a ring that fits the base, and off the ring at the gurgle. Keep the base of the pot clean and flat so it touches the glass evenly.
Induction
Induction only heats magnetic metal. A classic aluminium pot sits on it and does nothing. Stainless steel pots with a magnetic base work, and so do some aluminium pots made with a steel plate in the base.
An adapter disc, a flat steel plate that sits between the hob and the pot, works with any pot, but it is slow and gets very hot. With a disc I start with hot water and keep the setting moderate.
Outdoors
On a camping stove, shield the flame from the wind and keep it small; a gust that blows the flame up the sides has the same effect as a burner turned too high.