Ham keying subwoofer

[T4RNightHawk]

Whenever I key up on my handy talkie my subwoofer thuds. At first I thought this was because my radio was plugged into the 12v and I was having a grounding issue but then using the battery it still picked up the signal? I have the subwoofer RCA cable coiled under my center console so could it be something with that where the signal and coil are acting like an inductor or something?

 

[DMX512]

Just spitballing here but...
You might try moving the slack farther away from the transmitter/antenna.
Coiling the slack in a figure eight pattern instead of a loop "might help".

 

[RonJR]

Pretty common issue with audio amplifiers around RF sources. The cable input to the audio amp picks up the RF and introduces it into the amplifier. The amplifier can't respond to the RF linearly, so it rectifies it and turns it into a DC or low frequency thump or signal. In some cases you'll hear your handy talkie audio on it.

The root cause is improper routing of the cable grounds inside the subwoofer. That's a design/manufacturing problem that is well understood, but the audio manufacturers, even high end ones, still routinely do it wrong.

The advice to try re-routing the RCA cables is probably your best bet. Also make them as short as possible. Make sure the RCA grounds are making good connection at the subwoofer - they're notorious for not doing that. Take a pliers and bend the ground tabs carefully inward until they fit really tight on the RCA jacks.

 

[T4RNightHawk]

Pretty common issue with audio amplifiers around RF sources. The cable input to the audio amp picks up the RF and introduces it into the amplifier. The amplifier can't respond to the RF linearly, so it rectifies it and turns it into a DC or low frequency thump or signal. In some cases you'll hear your handy talkie audio on it.

The root cause is improper routing of the cable grounds inside the subwoofer. That's a design/manufacturing problem that is well understood, but the audio manufacturers, even high end ones, still routinely do it wrong.

The advice to try re-routing the RCA cables is probably your best bet. Also make them as short as possible. Make sure the RCA grounds are making good connection at the subwoofer - they're notorious for not doing that. Take a pliers and bend the ground tabs carefully inward until they fit really tight on the RCA jacks.

Yea I'm thinking I'll cut it to size and put banana plugs on it.

 

[RonJR]

While banana plugs are awesome for low frequencies, they don't shield out RF effectively. You'll be better off with the RCA's. If you want to put on a better connector, use a type F (TV cable) connector and make sure the shield braid is crimped solidly to the connector shell all the way around.

RF is funny stuff, and things that seem obvious aren't. Very short ground paths especially are absolutely crucial. By short I mean 5mm is considered long.