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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?
128x128fossilsx15
sbank's avatar
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????
almarg's avatar
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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
sbank's avatar
sbank
3,378 posts
 
Copper is a lot safer than lead, and would provide the same benefit. If you go this route research the term, "Faraday Cage", which is a lab quality box. The problem is that you need cables going in/out and that often corrupts the ability keep out the RFI.

Borrow a solid state phono stage before you conclude anything else or spend big bucks. Trust me, I struggled w/this crap for YEARS! Cheers,
Spencer
fossilsx15's avatar
fossilsx15 OP
19 posts
 
Al & Spencer thanks for your input.

Al -- my cartridge is a Grado MM. Would you please exlaborate what sort of capacitors to use. I'm not too electronically literate.

Spencer -- I did hook up to a solid state phono stage. Did get RF, but was able to manipulate the turntable ground and this eliminated the RF.

Here's something more puzzling. When I re-plugged my turntable into the Rogue 99 tube phono stage, I noticed that the RF disappeared when I touched the pre amp. At first it was my arm on the pre amp with my fingers touching either the turntable ground wire or the turntable leads. I thought great, if only I can find a spare arm to leave on top of the pre amp. The heat would probably make it stink up my living room though. Then I realized if I simply touched the pre amp, the RF disappeared. I tried a separate ground to the pre amp, but this did not prove successful: the RF was back. Yet, when I laid a hand or fingers on the pre amp, the RF disappeared.

If you guys have any more suggestions, I'm game. I feel now, there has to be a simple solution, I just don't know what it is.
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