MTP30N06 mosfet instead of STP55NF06

Hi all,
Ive got a hard time finding the exact mosfet type for ramps, so instead of using the stp55 one, I am planning to use the obsolete mtp30n06 (this was available here). Will this become a problem?
In other words, do we really needs 55 Amps? could I just use 30 Amps for heater?

Second question, if I just wanted to test the X, Y, and Z axis stepper motor, without heater support, is it ok to run the board without the mosfets assemblied?


Sorry for my english,
thx & best rgds,
Ajiehestya

Edited 2 time(s). Last edit at 02/26/2011 11:33AM by ajiehestya.

30Amps should be fine. You may want to heatsink your MOSFETs though. Check out the Ron value isn't too high though.

You can test your motors without the FETs mounted. It won't cause any issues.

Ron value is 0.080 ohms. Is this acceptable? Compared to the stp55 is about 0.012 ohms.

Should be fine then, but as mentioned, you may want to use a heatsink, as it won't be quite as efficient.