Hi, i am very new to r/c helis. I have figured out all of the radio controls but one. I have a Futaba skysport radio and the control I can't figure out is the hov. pit. knob. I think it has something to do with bias between the main rotor and tail rotor controls. Can anybody explain it to me and maybe where I should have it set? I have a Kyosho Concept 30 SR.

As fintenfyr said, it is used to make fine pitch adjustments in hover. I have a JR radio and on mine, it essentially adjusts the middle point on the pitch curve up or down. There is also a hover throttle knob which does the same thing to the throttle curve. Both knobs affect normal flight mode only, not the idle ups.

While you should set your curves up to work properly with both knobs set to zero, or centered, I sometimes use these knobs to play around with different head speeds while hovering, without the hassle of changing the curves.

It does not affect the tail rotor unless you have some wierd mixing function programed. I suppose revo mixing (mixing throttle with rudder) could cause the hover throttle knob to affect the tail servo. If you have a heading hold gyro, you should disable any revo mixing.