[RFI] Subwoofer does CW

[Hare,Ed, W1RFI]

> I don't want to pop in every other day with a different idea so I want to 
> gather as much info as possible and make one assault.

Even at that, it is a good idea to warn him that these things can be complex and that RFI has a number of different cures that may need to be tried. That way, if the first few don't work out, he will remember that you expected this. Otherwise, if he loses confidence in you, he will tell you to go away and fix the problem at your station. Unfortunately, for audio RFI, that simply won't work.

Industrial Communications Engineers does sell a line of audio filters. See:

http://www.arraysolutions.com/Products/ice/

73, 
Ed Hare, W1RFI
ARRL Lab
225 Main St
Newington, CT 06111
Tel: 860-594-0318
Internet: w1rfi@arrl.org
Web: http://www.arrl.org/tis

ARRL is the National Association for Amateur Radio.  It is supported by membership dues, individual contributions and the sale of  publications and advertising. For more information about ARRL, go to http://www.arrl.org/news/features/inside-your-league.html. For more information about membership, go to http://www.arrl.org/join.html.  Your contribution can also help support ARRL's ongoing efforts to protect Amateur spectrum. Go to https://www.arrl.org/forms/development/donations/basic/ to learn more about the ways you can support the ARRL programs and activities of most importance to you. You can help ARRL protect Amateur Radio for you and future generations to enjoy.


> -----Original Message-----
> From: Tom Hoyer [mailto:hoyer@netreach.net]
> Sent: Saturday, November 23, 2002 8:42 PM
> To: rfi@contesting.com
> Subject: [RFI] Subwoofer does CW
> 
> 
> 	Just came back from my neighbors house after trying to 
> fix his subwoofers.
> They seem to like to receive my 80 meter cw signal. 40, 20, 
> 15 and 10 are
> clean. I use a vertical on 40 with a matching network at the base that
> switches in a loading coil for 80m. If I use the matching network, the
> interference is louder then when I use the vertical without 
> the matching
> network and tune it with the internal antenna tuner of my 
> xcvr. Interesting.
> 	He has 2 subwoofers. The first one does not react when 
> the speaker cables
> are disconnected and just the power cord is connected. The 
> second one reacts
> with only power applied. The level of interference does not 
> change with
> volume level. I tried clip on ferrite beads on each speaker 
> cable, with no
> effect. Of course I do not know what core material these beads are.
> 	My next step, I suppose, would be to use a power line 
> filter on the second
> sub woofer. The first one I probably need to disconnect 
> everything from the
> system and connect one at a time to find the offender. Does 
> this sound like
> a reasonable approach? I don't want to pop in every other day with a
> different idea so I want to gather as much info as possible 
> and make one
> assault.
> 	Does anyone have experience with this type of problem?
> 
> 	TNX,
> 	Tom  W3TA
> 
> PS TX power is 100W and the antenna is about 100 feet from his house.
> 
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