Radio Hum
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Joined: Nov 2010
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Radio Hum
My 2011 FLHTCU Harman/Kardon radio has a constant low volume hum through all four speakers when the unit is turned on with all input settings. The radio has never been removed and has not been exposed to rain. I previously added Boom Audio front and rear speakers. Don't remember hearing a hum with the OEM speakers. Any troubleshooting tips would be welcomed.
Road Master
Joined: Aug 2015
Posts: 768
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From: chico
cycle electrical systems emit RF. I suspect the your speaker wires are acting as a coupled element, an antenna, and picking up electrical emissions from the bike electrics. audio cable ought to be run inside grounded braid. ground both ends of braid.
braid?
find some old coax and strip away the guts, leaving braid.
or buy audio cable that's already made with braid.
of course I don't know - maybe the bike's switched off - you might disconnect battery and radio power input and then power radio directly from an isolated independent power source - like another battery. and maybe it's the neighbor's noise...
ARRL has good advice on suppressing ...
chasing down stuff like you describe is often more art and intuition than anything else...
good luck!
braid?
find some old coax and strip away the guts, leaving braid.
or buy audio cable that's already made with braid.
of course I don't know - maybe the bike's switched off - you might disconnect battery and radio power input and then power radio directly from an isolated independent power source - like another battery. and maybe it's the neighbor's noise...
ARRL has good advice on suppressing ...
chasing down stuff like you describe is often more art and intuition than anything else...
good luck!
Road Master
Joined: Jun 2010
Posts: 1,221
Likes: 4
From: Annemasse (border of Geneva-Switzerland) facing Mt-Blanc.
If you hear the HUM when the engine is off you may have an "open" input.
To check your amplifier when you have an "aux" input connect both hot wires to ground, select "aux" then the speakers must remain quiet in their 'zero' position.
Then turn the engine on to check supplied voltage variations: the speakers should again remain quiet.
Sometimes the CD player motor will inject it's parasitic "signature" so start with the inputs if you can. A 'zero' voltage between hot and ground leads of an input will produce a 'near-zero' output voltage. This is a common test.
Don't short the amplifier output though
To check your amplifier when you have an "aux" input connect both hot wires to ground, select "aux" then the speakers must remain quiet in their 'zero' position.
Then turn the engine on to check supplied voltage variations: the speakers should again remain quiet.
Sometimes the CD player motor will inject it's parasitic "signature" so start with the inputs if you can. A 'zero' voltage between hot and ground leads of an input will produce a 'near-zero' output voltage. This is a common test.
Don't short the amplifier output though
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