How to eliminate FM RF coming thru turntable?

I would try to shield as much of the phono leads as possible.In some cases this may be as easy as replacing an unshielded wire with a properly shielded one or as difficult as trying to wrap delicate leads from your cartridge with shielding. It could also be the cartridge itself that is picking up the RF - try switching carts to see if the problem persists or changes.

Can you isolate the frequencies of the FM signal? On an active guitar pick-up system (a Gibson ES- Artist) that had RF issues I could even hear the program material (it was an AM religious station).

You may be able to do electronic shielding if you can identify the frequencies that are bleeding through, but an electronic filter may have an audible effect that is more pernicious than the original problem.

Quoting from a response I made a while back when someone else had a similar problem:

I believe that oxidized or dirty contacts can cause that, particularly as here where low level signals are involved that are subsequently subject to high gain. The poor contact results in diode rectification effects, which demodulate the radio signal.

Try using some contact cleaner on all of the connections that are involved, including the ones in the headshell that mate to the cartridge pins, as well as any other connections that are in the path to the phono amp. Or, as a minimum, just slide each of those connections off, and then back on -- that might rub off the oxidation sufficiently.

Also, I assume that you hear this pickup with your FM tuner turned off. If that's not the case post back.

Good luck,
-- Al

Almarg...A corrosion-formed diode can indeed rectify an AM station's signal so as to produce recognizable audio. In my experience what you usually get is a mixture of several stations, some louder than others.

However, it takes a lot more than a diode to pick up recognizable audio from a FM signal.

A corrosion-formed diode can indeed rectify an AM station's signal so as to produce recognizable audio. In my experience what you usually get is a mixture of several stations, some louder than others.

However, it takes a lot more than a diode to pick up recognizable audio from a FM signal.

Hmm, yes, you have a good point there.

But still, if we understand the facts correctly (recognizable audio from fm, being introduced through the phono input, and present (I assume) when the fm tuner is turned off), SOMETHING in the phono path is somehow demodulating the signal. Not sure what that could be.

Regards,
-- Al