I just used the Spectrum DSP to setup my DSP75 tail rotor servo on my Blade 400. Wow, what a difference. I was easily able to precisely set the center and end points directly in the servo without any mucking around with the transmitter settings or servo arm. Nice!

More importantly, all the Spectrum programmable servos, including the DSP75 (which many of us are using on our tail rotors) come setup for airplane use. The DSP lets you select one of three operating modes for the servo - Airplane, Helicopter, or Tail Rotor. Changing to tail rotor enables much higher gain (faster response) in the servo. It made a real noticable difference in my otherwise stock setup. You can also change the reverse setting directly in the servo so you don't have to change settings on the gyro or in the transmiter. That eases the replacment of the stock servo and avoids complications.

I highly recommend the Spectrum DSP if you have any of their programmable servos. It cost about $25 at most outlets.

Sounds like a cool product.

This might explain why the servo didn't seem to perform much better than stock when I swapped out the rear servo for this unit. I asked around about the programmer to a few online stores and got told that it didn't do much of anything except allow reversing, which you could do in the TX.

Now I see they were wrong.

I was initially under the impression that you could use the DSPs on the collective. I found that they had to be re-programmed first..

I have a DSP on the tail of my Blade 400 (no reprogramming needed for that) and it is rock solid...

-Damon