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Author Topic: POWERED SUB WOOFER PROBLEM  (Read 21437 times)
W9DEC
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Posts: 49




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« on: June 30, 2013, 04:16:00 AM »

I have a big powered sub woofer that makes a tremendous noise when ever I open a microphone on any of my radios. The problem goes away when I unplug the sub. The noise from the sub when I transmit is extremely loud. Any suggestions on what I should do?
« Last Edit: June 30, 2013, 04:25:34 AM by W9DEC » Logged
WX7G
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Posts: 5917




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« Reply #1 on: June 30, 2013, 07:21:50 AM »

The simple solution is to unplug the subwoofer when you're on the air.

Another fix is to place ferrite cores on the subwoofer leads. You can try cores on the AC power and audio leads separately or together. That is with both leads through the same core.

DX Engineering stocks snap-on cores that might do the job. 

http://www.dxengineering.com/search/part-type/rf-suppression-snap-on-ferrite-beads?tw=ferrit&sw=RF%20Suppression%20Snap-On%20Ferrite%20Beads
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KB4QAA
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Posts: 2260




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« Reply #2 on: July 02, 2013, 02:14:42 PM »

Standard Checklist
-Reduce power
-Change bands
-Re-orient antenna
-Move antenna further away
-Organize shack, separate all cables, coil them up, add chokes
-Add chokes to your speaker cables, computer/stereo
-Unplug the speaker
-Use non-amplified speakers

p.s. Palomar Engineers also has a nice RFI kit for $35, with quite a number and variety of chokes.
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K0JEG
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Posts: 631




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« Reply #3 on: July 02, 2013, 08:05:33 PM »

I recently moved, and installed audio cable in the crawl space and walls. Since I was going to all that trouble, I spent a little more on 14Ga twisted pair wire. Nothing esoteric, the big difference over the super cheap stuff being that it's twisted pair.

My subwoofer still powers up when I transmit, but instead of hearing a lot of my voice when I transmit I only hear a slight thumping. Note the line from the amp to the sub is about 25 feet and line level, not amplified. None of the other speakers (which get amplified signal) have any interference. I'll likely add a few ferrites to the subwoofer input (and inside wiring if needed), but a big improvement over the situation in my apartment where I had to unplug the subwoofer (but antenna is about 20' further away than the apartment too).

http://www.crutchfield.com/p_70314250/AudioQuest-FLX-14-2-14-Gauge-2-Conductor-In-Wall-Speaker-Cable-50-feet.html

Note: I did NOT pay attention to the signal direction arrows! Roll Eyes
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W9DEC
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Posts: 49




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« Reply #4 on: July 03, 2013, 02:46:39 PM »

 I bought a plug with a remote so I can turn off the sub from my easy chair or the shack and I also added ferrite beads to the rca line and power line on the sub. That seems to have solved the problem.
73
W9DEC
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