Re: Radio noise despite it being off
Yes I do.
Ok sorry I'm a bit punchy today, spend most of the day up on a crane where it was like 120 degrees F. Ok, battery chargers have coils and pots in side of them that convert 110ac down to 13-14vdc. These coils and pots physically vibrate as they convert Alternating current to Direct current, this is why your charger hums.
The energy they produce is often "dirty" and not true DC (it oscillates slightly) thus creating noise in the line. When charging a battery this is not a problem cause your stuffing energy into a battery. However when your running sensitive electronic equipment off a battery charger, the equipment is looking for true DC and does not require noise suppressors and other stuff to block out the signal. When noise is inserted into the line either in the form of dirty power or RF it makes it's way through all the electronics and causes the radio to hum. This humming would also be very apparent on the TX side of the radio (people listening to you talk while that charger is on would hear a loud audible hum).
The reason you hear the noise even with the radio off is because most radios never really turn off, most go into standby. They still consume some power to keep things like the channel memory or user preferences from going away and needing to be reset every time your turn the radio back on.
The noise isn't bad for the equipment, and shouldn't hurt it. To get rid of it you can turn off your battery switch when you charge(not a bad idea anyways) or you can try to install a noise suppressor like the ones used in cars in line with the positive wire going to the battery.
Also check your connections very well especially your ground going to your battery.
http://www.crutchfield.com/App/Product/Item/Main.aspx?g=181150&i=003S25A&search=noise&tp=2653
Bill
