I have a dragonfly 36 cp helicopter,being used to flying fixed pitch the change to collective was quite different.

I can hover fine but i find i cannot keep a constant height,the heli seems to jump up in spurts and go downwards in spurts also,i cannot get the heli to be stable in height,yes i know you do have to actually fly these cp helis but it just feels not right.

I have adjusted the pitch servo arm position to a closer hole to the centre of the servo as suggested before but this has not cured the yo yo effect.

Any suggestions would be greatly recieved.

That is a common problem going from fixed pitch to a collective machine. If you could see your fingers/thumbs you are over controlling the collective. It is not like a fixed pitch where you can throw the throttle up and down rapidly. A collective machine must be flown with finesse. Subtle gentle movements on the collective just like a properly setup cyclic are necessary. Slow down and practice lifting off and landing until you get the feel for it. All this assumes your machine is setup properly.
Gary

Thanks for that advice Gary,is there anything with the setup of the heli i can do to calm down the cyclic inputs on the throttle/pitch.

Cheers

Unfortunately that is one of the disadvantages of the Tx that is supplied with most ready to fly Helis. It lacks the swash adjustments you find on more sophisticated computer radios. Other than moving all of the links in closer there really is not much you can do. One thing to be aware of though, moving the links in will restrict the amount of pitch available and may make the bird even harder to fly.
Gary

Make sure there is no binding in the head, if you have a sticky pitch action you will get the hop and drop effect you describe