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How to eliminate FM RF coming thru turntable?

Mitchell GYRO SE turntable picking up FM RF after 5 PM to late at night. During the day, no FM RF being picked up by turntable. All other components, no RF (tuner, CD, tape). All components connected thru Furman power conditioner. Have run separate ground from Furman to turntable ground at preamp (Rogue 99) which reduces the FM RF considerably, but does not eliminate. FM interference reacts to volume control. FM RF disappears when turntable leads disconnected. Any suggestions?
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almarg's avatar
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almarg
9,670 posts
 
Here's an excellent paper, dealing with rfi problems caused by ham radio systems, but providing a lot of information that may be applicable to your situation as well:

http://www.audiosystemsgroup.com/RFI-Ham.pdf

Here's a link to the catalog of Fair-Rite, which makes a lot of these things:

http://www.fair-rite.com/newfair/index.htm

Radio Shack (you'll pardon the expression :)) sells some snap-together ferrite choke cores, part numbers 273-104 and 273-105 according to an older catalog I have.

Hope that helps,
-- Al
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fossilsx15 OP
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Almarg, thanks for the article and link to suppressors, am pursuing --
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sbank
3,378 posts
 
mouser.com also sells cheap ferrites.
fossilsx15's avatar
fossilsx15 OP
19 posts
 
I tried ferrite suppressors which didn't work: cable suppressors and ferrite beads.
Someone suggested lead sheets to line thecabinet the turntable sits in -- if Superman can't see through the stuff, then maybe radio wave as well -- anyone have any thoughts or knowledge????
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almarg
9,670 posts
 
How about the other suggestion I had made, adding a small amount of capacitance via a y-connector at the preamp inputs (the capacitors being soldered to rca plugs that would plug into the y-connectors)? As I indicated, the only caveat would be to make sure you are staying within the range of total load capacitance recommended by the cartridge manufacturer. If you have a moving coil cartridge, load capacitance is most likely very non-critical.

Regards,
-- Al
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