2m Feedback into sub woofer

[NAILER341]

WTF is causing the feedback into my sub woofer when I key the mic on the 2m radio?
2m is grounded to the battery. Sub (powered) is grounded right where it is mounted.
Antennas are pretty close to one another on the roof. They are within a foot of one another. The 2m antenna ia about a foot tall and the stereo antenna ia 3.5' tall. Might this be the problem?
I have already blown one sub, and I hate to keep doing it.
There has to be a simple fix for this.
Any suggestions?

[Russ Chung]

Erik,

Here are some things to try:
1. Make sure that the sub woofer lead wires and the 2m antenna cable are NOT coiled. If the subwoofer wires are too long, cut them instead of coiling them up. If the antenna cable is too long, cut it or re-route it, but don't coil it. Coiling any excess wire will amplify any interference.
2. Separate the sub woofer lead wires and power wire from the 2m antenna wire. If the speaker wires are on the driver side of your Jeep, route the 2m antenna wire up the passenger side of your Jeep, or vice versa.
3. Make sure the sub woofer and the 2m antenna have good ground connections. If in doubt, run a ground strap from the sub woofer ground to the battery and from the 2m antenna mount to the battery.
4. Install ferrite beads on the sub woofer lead wires. http://en.wikipedia.org/wiki/Ferrite_bead You can buy ferrite beads at Radio Shack or Ham Radio Outlet.
I don't think that having the 2 antenna and the stereo antenna close together would cause the sub woofer failure. I would think that it would cause problems for the stereo amplifier before it would cause a problem for the sub woofer.

Russ

[NAILER341]

Great info Russ. I will do this to try and correct the issue.
On a side note, the Sub has a built in Amplifier.

[CVD]

Russ – is “no coils in 2m antenna cable” a universal recommendation, or just when debugging problems like Erik’s?

[Russ Chung]

Clif,
It's a universal recommendation. Whenever you coil a wire, whether it is a CB, 2m, AM/FM radio antenna or a power cable, you change the inductance of the wire which could cause it to radiate or to receive stray signals.
Russ