Again, thanks for the suggestions. Makes no difference whether the lights in the house are on or off. For the renovation, the entire house was rewired. I have a dedicated circuit for the stereo. I tried plugging the equipment into different sockets on different circuits: made no difference to my problem. Did read that radio broadcasts are different at night, thus getting the signal when the signals are altered. It's the same FM station and begins around 5- 5.30 PM until after midnight. During the day, absolutely dead quiet. My phono stage is tube. Tried changing the tubes in case one or all were picking up the RF.
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?
- ...
- 26 posts total
Some FM stations also broadcast on AM (or used to). Since demodulating FM by accident is virtually impossible something like this should be investigated. Many AM stations are required to REDUCE power at night because the signal travels so much further...to places where another station operates on the same frequency. Are there any practical jokers near you? |
I had a very similar problem also with a gyro se using a stock rb300 arm. In my case it was the tonearm cable picking up an am signal, I have no idea why but I was able to virtually eliminate it by reversing the phono inputs into the phono pre (plugging the left phono plug into the right input and right plug into left input) of course then I also had to reverse the leads from my phono pre to my linestage. Don't know if that's an option but it's easy to try. |
The RF I'm getting could very well be AM, I haven't listened to AM for years, so made this mistake, regardless, still getting RF at night, Spanish speaking talk radio -- any suggestions on brands of a ferrite RF filter? Will also try switching the tonearm cable. Again, thanks for all the suggestions. |
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 |
- 26 posts total