It sounds like you have the same issue as me then.
What I have now is a 470pf capacitor, in series, in the ground of the coax cable going to the radio unit. The only thing I may need to check is whether this is of the correct spec as you are using FM, and the frequencies are different to DAB. What i would suggest is that you try a 1nf capacitor first and see how you get on. You could go lower if there is still noise but that might affect the signal quality, maybe.
It's also possible that grounding the Venice7 module directly to chassis could help but I wasn't prepared to solder anything onto it and void any warranty it might have.