Hi,
I'm sure this is common knowledge, but not where I fly.
I changed one of my Jets over to RadioMaster Tx16S following the failure of the screen on my Graupner MZ24. I thought I'd set everything up correctly but after take off it was clear the model was severely nose down. I couldn't get the elevator trim on fast enough so landed rather than persevere. (I was getting in a right mess. Being Mode-1 I had to let go the right hand side of the Tx to reach the elevator trim with my right hand - couldn't let go of the L.H elevator stick!)
Once on the ground I sub-trimmed the elevator to where I thought it should be and attempted a take off. With T/O flap selected the model rose parallel to the ground but refused to pitch up. Shut the throttle and carried out a very fast landing.
When I got home I checked out what had happened. Turns out that on this Radio, the trim eats into servo travel, i.e. 20% up trim means only 80% remaining up-travel. I use 67% Expo. so basically had no up elevator. (Glad I aborted!) I'm used to the trim changing the entire arc of the servo - it never occurred to me this is not the case here. Took forever to find a way round this, however here it is:
Set 'Model setup' to 'Extended Limits' on stick travel,
On the 'Inputs' screen set these at 80%,
on the 'Mix screen' set at 100% and
on the 'Outputs' screen set +/-125% travel.
Hope this helps - (I have to say I've found a lot of spurious advice on the 'net.)