Tremendous RF problem -- phono stage is a radio

Time to change tubes...

What is your specific equipment and how close to a radio station tower do you live?

I live in an area prone to RF interference, and I had problems with my previous preamp, a Copland tube model. It picked up taxi radios, among other things. When I switched to a Klyne SK-5a, the problem went away. It could have been the Copland's design, or it could have been the tubes.

Have you tried different lenghts of cables? The interconnect may be the proper antenna length for your local radio stations.

RFI can come through your windows and changing cables (or wrapping them) or tubes may do nothing. You might just try turning the amp 90 degrees to see if it changes anything (but it's unlikely)

I used to live in a location with bad RFI - different radio stations from each speaker! - and the way I ended up solving the problem was to locate the stereo in the part of the place that was below ground level (and no windows either) and have the speaker cables come up through the floor. It worked beatifully.