22k will not work. a 20k variable resistor has three legs, and varies 0-20k ohms between legs 1 and 2, and 20k-0 ohms, between legs 2 and three, when turning from fully counterclockwise, to clockwise.
As you can see, you could have any combination of resistances, but with a 22k, not only are you over the value of the pot, you wont be able to adjust to, say, 6.5k ohms. In short, get a pot.
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