Tremendous RF problem -- phono stage is a radio

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.

You might get lucky with changing tubes or cables, but it's unlikely and it's just a chance. The best thing is to shield the phono stage. There are a variety of ways of doing this. Most RF can be shielded by a wire cage that is tied to ground. There are other shielding materials such as "mu" metal that are also very effective. I had the same problem in one home and was successful with a piece of mu metal above and below the unit. The best shields enclose the unit entirely, but just like an antena that works best at a certain location, shielding can often be "incomplete" and still get the job done.

Rives...For many years I used shielded 300 ohm twinlead for FM signal. I am in a weak signal area, and noise from autos on the nearby road was a problem. It worked very well, but the surprising thing was that the shield was, by design, not tied to ground at either end. It was floating.