How to eliminate FM RF coming thru turntable?

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

Thanks for the suggestions -- will give them a try. Just completed a year long renovation. The equipment was originally in the center of the house and rarely if ever had an RF problem. Now, equipment is housed in a wood cabinet against an exterior wall. A new FM antenna is about 10' from the turntable on the eaves. Disconnected the cable to the antenna and still have RF signal. The same station comes in when the night signal changes. It makes no difference whether the tuner is on or off with the RF. Again, during the day, phono is dead-quiet.

This is just a wild guess, but since it's only happening at night, could it somehow be related to the fact that lights are on (vs. during daytime)? I'm no electrician, but it seems that the difference between night and day might be the clue here. I wonder if the house wiring is somehow acting as an antenna/repeater (from the renovation you mention) is causing the issue, but only when the circuit is closed such as when lights are on.

Again, a wild-assed guess at best but logic dictates ruling it out as a cause.