Hello,
I know the problem with the radio reception with the phono amplifier well. When I was young, I searched for quite a long time until I found the cause. The interference comes through the output of the phono amplifier and finds a parasitic path to the input. The HF signal is demodulated on the characteristic curve of the tube and is then further amplified as an Audio signal. You have to install capacitors to ground at the output of the phono amplifier. Possibly also resistors in series so that a low-pass filter is created in the back direction to the phono amplifier. So opposite to the direction of the signal. The whole thing is dimensioned in such a way that it does not affect the Audio frequency response. Capacitors with some 100pF. Resistors must be tested. A Trimpot could help to find the best value.