[Dominik]

Just by looking at it totally electrical:
the resistance could be changed by using resistors in line or parallel.

i.e. two 100 Ohm resistors in para result in 50 Ohm total.

one 100 Ohm and a 50 Ohm in para result in 100+50 / 2 = 75 Ohm.
Two 100 Ohm in line - you guessed it: 200 Ohm total.

Matching it exactly through the hole range is a real challenge ...

Dominik