On the subject of wired things my 35 upset telly reception for some reason
We had a motorbike did that .....................
Stick a suppressor on the dynamo and/or ignition coil, see how you go.
Click for an example, £3 would be plenty to pay ...............
Its a bit of a black art, so you might have to try a few things to kill it fully .............
InterestingI had a TED 20 that did the same to next doors telly even though they were well over a hundred meters away it did it to our telly too but when the tractor was in use we were always out so did not realise it was having this effect until he complained, a suppressor on the dynamo cured the problem.