This is off-topic, but it does have to do with a transmitter, so maybe it isn't all that off-topic.

I'm thinking of getting one of the c-crane fm transmitters to connect to the output of the sound card on my pc so I can listen to streaming audio in other rooms of 
the house.

I've heard the power on this transmitter is extremely low but it can be increased (and is even probably still very legal) by removing a name plate on the back 
which exposes 3 screw holes.  Apparently the one on the left is the power level.  

Does anyone happen to know what the other two adjustable screws are for?  

I can't seem to find any technical info on it.

Thanks,

73

Don  W6SMB