ok this is my second post on this issue. i had a power supply that was just able to handle my dx 400 on medium power, 35 amps or so. when i keyed up and started talking it sounded like my voice was coming through the power supply, weird shit huh! i mean loud as hell to. my buddy suggested to put a 3.5 fared capacitor in line with it. like my maybe not enough power or something. holy shit! i worked like a charm! i had my old lady whistle into the mike and i held my ear against the power supply and couldnt hear a thing. hooray!!!! like i said when you whistle into the mike without the capacitor you can hear your voice in the power supply just like a distorted talk back. ive never heard someone using a car stereo big ass 3.5 fared cap with a volt meter in a ham shack before. so anyway a coulple of guys suggested my power supply is to small and get a bigger one. cant argue that, hell you need atleast a 50 amp supply to run that amp, 4 pill dx400. not a 35 amp supply. so i just got a mfj 75 amp switching, mfj-4275mv power supply. up to 16 volts and all that happy shit. guess what? as soon as i got it hooked up i set the amp on med power with a 2 watt input which would give me a 100 watt dead key and up to 300 watt swing and what ya know my voice is coming trough the power suppy again or vibrating trough what ever you want call it. what the hell is going on here? im running a hr-2510, turner plus 3 mike, 75 amp mfj-4275 switching power supply, texas star dx-400 amp with 100ft of cable xperts rg213 coax and a maco 5/8 wave antenna thats 35 ft up in the air. im pushing 2 watts into the amp also. put the 3.5 capacitor on it and its fine. leave it out and you can hear your voice vibrate through the power suppy loud as hell. every word you say like a fucked up talk back. how is this? i didnt know power supplys had speakers in them. its not the amp or my radio. i also tried ferrite beads, made it worse. checked grounds and the whole nine. the likely hood of someone figuring this one out is slim. guess im gonna have to run a 3.5 fared capacitor like a filter after my power supply then to the amp. why does the cap solve the problem totally? is it severe ocillation and how can i stop it? i also noticed on high power i have backwards amprege