This might be a little DUH.. but..
what I do now is just put in two tablespoons of
coffee..in the strainer..
then, fill my coffee cup up and pour two cups
from the cup in the machine.
What I did before was make about 4 cups using the
coffee pot as a guide for the water.
I don't drink coffee, but at work before we got an employer funded
coffee service, my coffee-addicted colleagues would simply put a
teaspoon or two of coffee in a cup with cold water and nuke it for a
couple of minutes. Now, we get free coffee (via an industrial size
coffee maker) and hot tea, so this practice has ended, but its also the
same way my dad makes his morning coffee.
That probably still works, but if you reduce the amount of coffee
compared to the diameter too much, it may affect the consistency
of the brew.
BTW, I use a heaping tablespoon for every 2 cups of water going in.
Don