I'm setting up a plane and want to get the most resolution out of my servos. So I set my arms up for a 1 to 1 ratio, but to get a good 45 degrees throw on my elevators I had to dial in travel to almost full (150) on the DX9

The problem is when I go into DR and expo and try to set a high rate (maybe about 50 degrees) the RIGHT elevator moves down to the 45 degrees and then stops. while it will move UP to the full 50 and hte left one will move up to 50.

What appears to have happened is the RIGHT elevator doesn't center on the gear as well. So I had to use subtrim to get it to center up. That in conjunction with the travel makes it bottom out on the monitor when moving DOWN but not up.

My quesiton is, these servos (if moved manually) can move MUCH further than what the radio is requesting. They can move 180 degrees. but the radio is only allowing a max of about maybe 120. Is there a way to get the radio to allow more range of the servo?

Maybe a better question is - is there a great source/web page for basic servo /radio set up to help me understand all this better?
thanks!

Most servos can travel 120 deg, 60 deg in each direction. Just because you can turn the servo arm by hand further, doesn't mean the servo's internal electronics will support more than 120 deg.

I'm not quite sure what you meant by "I set my arm up for a 1 to 1 ratio", but if you mean the linkage connections on the servo arm and at the control surface are the same distance out, that is not necessarily optimal. Shorter at the servo and longer at the control surface gives you better mechanical advantage. In your case, I would dial the travel back to 135 or so (so that you have travel left for your trim levers to use) and set up my high rates (dual rate at 100%). You will have to move your linkage in on the control surface and/or out on the servo arm to achieve the throw you want (as opposed to dialing up the travel). Although you'll lose some mechanical advantage by doing this you can probably go to a higher torque servo if you experience blow back in flight. Then I would set my low rate throw by dialing down the dual rate percentage.

What kind of plane is this? 45 degrees is a huge amount of travel, even for a 3D type plane.
As for servo resolution, it's a good thing, but not something to stress out about. If you set up the servos with the standard 100% of travel and then adjust the clevises to get the recommended throws you need, you'll be fine. Back when radios only had 256 positions for the servos to go to resolution mattered. Now that it's 1024 on most radios and even 2048 on some, it really doesn't. What does matter is torque and gear wear, which having 100% travel helps with tremendously. But if you wind up at 90% travel when it's all done, there will be no difference at all in the flying characteristics of your plane when it's all done.

Thanks for asking the question Jester! And if I may, now on to some other questions I have that have been bugging me for several days:

1. How many servos are there and are they digital or analog?
2. Was the TX checked to be sure that all trim mods were removed?
3. Was any check made to insure that there are no mechanical limits to travel?
4. Are we really working on elevator(s) or ailerons?
5. Have the servos been checked for equal travel on either side of center?
6. How does a DX9 deal with multiple servos for a single function?

Question 6. is posed because my TX (Futaba 6XAs) has different throws for different channels (If not modified in software). In this radio CH 1-4 are only good for ~40 deg on either side of center, while 5 + 6 are good tor ~55 deg plus or minus.

I'm fully on board with RBacons. The mechanical setup needs to be "dead bang on" without any electronic intervention. The trims are there for just that, TRIM, after the bird is in the air. 70 years of dealing with life has taught me not to use up "wiggle room" to soon.