This forum is dedicated to discussions pertaining specifically to the Motorola ASTRO line of radios (those that use VSELP/IMBE/AMBE), including using digital modulation, digital programming, FlashPort upgrades, etc. If you have general questions please use the General or Programming forums.
To do it properly you need the correct W3 interconnect board. I have in a pinch used a regular one but in order to turn the radio off and on you must jumper pins 20 and 22 of the db25 (either one) on the front of the radio and put a switch in it which turns the radio on and off. Now I have only done this to quick test a radio BUT I have no idea what the long term effects would be.
Oh I should add doing it this way, the power button on the W3 control head has NO FUNCTION.