reply to post by NotAnAspie
The "'58 Plymouth Fury" reference was a bit a of joke, I expect, because that's the "haunted car" that was in Stephen King's classic horror story
(One of his better stories, I think, though I still feel "The Stand" was by far the best.)
But back to the main subject.
If it's resonance from the heater, you may be able to fix the problem by something as simple as packing some
higher-temp-resistant rubber insulation around any input/output pipes. Anything that will damp down or disturb the thing's ability to vibrate
(resonate) can be effective. Ditto the main body of the thing.
With your vehicle it can be the same problem -- especially with larger areas of sheet metal or these days, even sheets of hard plastic. (The plastic
doesn't normally pick up the AM/CB resonance, but it can amplify it from a metal part that did.)
You know how sometimes in a vehicle, there can be something that "buzzes" or vibrates at a certain engine rpm? Darned annoying. I had this problem
with the dashboard of a car a while back and finally traced it to a couple of bolts that were a bit loose. I tightened the bolts to spec and that
ended the buzz problem.
Okay, so while that was due to resonance transmitted from motor vibration, the principle is the same. At just the right frequency, things can
resonate. Normally radio waves aren't powerful enough to be audible, but under some conditions the resonance from a smaller (metal) object gets
amplified through a larger one and we can hear it.
As for picking up CB -- yeah, that's actually not so uncommon. If someone nearby is using a pretty powerful CB then speakers in a car sound system can
pick it up pretty easily. Sometimes even a larger sheet metal part of the bodywork can do it -- and this actually is more likely than picking up AM
The easiest fix is to fit some sound deadening material inside the sheet metal to kill the vibrations. With a van, a few small lengths of medium-hard
rubber packing between the inner (pressed metal) frame and the outer sheet metal bodywork will usually do the trick.
I did this for a friend's van a few years back to kill some really loud motor-induced resonance he was getting in the van's bodywork. Took about ten
minutes to fit some rubber packing in place and -- job done.
edit on 24/12/12 by JustMike because: (no reason given)