Mobile Interference

  • Posted on: 30 March 2015
  • By: Mike

So after I got my ticket, of course I immediatly went about installing my mobile dual band Icom 208h.  Because I randomly toss ladders on my car, I didnt want to put my antenna on the roof, so I went about using a lip mount on the back of the hood.  After getting the radio installed, I was getting  a nasty interference.  I tried many things, including relocating the wire, tossing a magnet mount on the roof, and even ended up drilling a hole in the roof for a permanent NMO mount.

After installing the antenna, all seemed well.  I headed out briefly for a short trip the next morning, and the interference was back again.  (anyone have a brick wall????)  So... after getting back home, I pulled the radio out, to check inside it and make sure nothing was loose, and verify the programming, etc.  Put it back in, interference gone.

Ran out on a different errand later on that day, and low and behold, it was back again!   

Well, on a random whim, I reach down and unplug the charger cord for my phone.... and wow! Interference gone!!

So it turns out, that cheap phone chargers use PWM (pulse width modulation) to handle the voltage regulation.  This causes some reasonable RF interference when not properly sheilded.  

Off to Amazon I went in search of a new phone charger...  I found this nice Anker brand unit, that charges up to 5 devices.  It will charge at 2.4 amps per port, for a total of 8 amps combined.  It charges the phone great, and it does NOT have any interference issues at all!  It even comes with an FCC rating according to the Amazon description.

I am very happy with the outcome, and honestly, it cleans up the mess in the car...  Well some!