Radio Noise

["Al Powell" <APOWELL@agcom.tamu.edu>]

> From: HKravec@aol.com
> 
> Yes it does have the Bose system.  I'll try pulling the radio out this
> weekend when I travel from Alabama to South CArolina and see what happens.
>  The sound is very throttle sensitive, could this still be electronic???

Your sound is *almost  certainly* occurring in the radio speaker 
circuits.

1)  While driving, have a passenger FIND the noise.  They will need 
to put their ear next to each part of the dash, and pay specific 
attention to the area in front of each speaker.  My bet is that it's 
coming out of the speakers.

2)  If it relates to engine speed, it's normally RF noise generated 
by the alternator.  A large filter on the power line to the radio is 
likely to be the solution.  Alternator noise is a whine which generally rises 
and falls in pitch "zzzzEEEEEEEeeeezzzZZZEEEEEeeee" as you rev the 
engine and then let the revs drop.  Noise from spark plug wires is more 
like bacon frying.

You won't find anything out from pulling the radio - all you'll see 
is the connectors which seat to it.  HOWEVER - nothing would be lost 
if you popped off each connector and made sure none of the press-on 
wire connections had backed OUT of the connector.  I have sometimes 
seen this occur, and I could see how a loose connector could cause an 
RF problem.

BUT - in the Bose system, there is no amp in the radio; the amps are 
located at the speakers.  Noise is generally only perceived after the 
signal has passed thru amplification.

If you find the noise is coming from only ONE speaker, it's probably that 
speaker with the problem (probably not a problem confined to one 
channel of radio output - this is less likely).  If it's coming from all speakers, 
it's most likely in the radio.  One additional possibility is the 
antenna.  This can be tested by connecting a standard 'Murrican fender 
mount antenna (I keep a $12 Radio Shack spare...) to a <German 
antenna connector to US-standard antenna adapter>.  If there's no 
noise with the substitute antenna, you know the problem is in that 
system.

Al Powell                           Voice:  409/845-2807
107 Reed McDonald Bldg.             Fax:    409/862-1202
College Station, TX 77843           Email:  a-powell1@tamu.edu 
W3 page - http://agcomwww.tamu.edu/agcom/satellit/alpage.htm
"Baseball is 90 percent mental.  The other half is physical"...
...Yogi Berra.