[RFI] RFI proof audio equipment recommendations

Craig Thompson craig at thompsonet.com
Fri Aug 17 14:26:39 EDT 2007

Thanks for the replies. Jim...your RFI tutorial is right at my side as I solved these issues. And Bill...there is hope. We have a wireless phone system that seems immune to RFI/EMI. And the same system is reinforced in the archives,the Uniden 5.8 GHz system. The V-Tech stuff not recommended. Also, I have called West Mountain Radio and you can't place an order until they are in stock. I will be calling them back around Sept. 1st. They said to watch their website for ordering. 
The SubWoofer is a terrible design from an EMI standpoint. Case is plastic, audio is rectified in the output stage. Any wire is an antenna. I stopped the pickup from the speaker and cable with a ferrite wound with the cable as well as replacing the cable with twisted pair. The input cable is still a problem. I tried bypass caps and ferrites...it is just a big antenna for the case. The inputs are unbalanced and the shield does go to the case. I took aluminum foil and lined the plastic case. I can now transmit aiming right at it with full power and not pick up anything except when I add the input cable...but that is unterminated. So it may be ok..have yet to test it with it connected to the preamp out. 
I still would like to hear from someone that has a subwoofer that does not pick up any RF. I don't need science projects!! I want to work DX and contest.
73, Craig

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