Radio ariel interference

[Curdster]

While the dash top was off decided to fit a new screen mounted ariel which is also amplified. It works great but only with the ignition off. When you turn the ignition on you loose the channel and just get a load of interference.
I took the new cable away from any other electrical wiring. No difference.
Checked the earth of the earth lead on the ariel. No difference.
Checked the live feed to the amplified bit of the ariel. No difference.
So why is the interference happening?
And before you all say just listen to the engine, I do and mainly use the radio for traffic updates.

[blueg33]

I have exactly the same problem

[RedSpike66]

Mee too in the Sag - never had a problem in T350... trip to Car&Bike for me sometime...

[Allandwf]

Mine has a dab fitted, ariel runs along the top cubby hole in the boot, away from engine.

[Curdster]

I have mounted the ariel on the windscreen bottom near side. I have move the lead well away from the dash so there is no interference, and I have move the head unit away from the dash too. Therefore the only issue could be that there is some electricals under the dash on the near side.
If this is the case, any ideas. Stupidly I have already stuck the ariel in place!!! Doh.

[Allandwf]

Isn't the fan n heater control box at that side? They are prone to burning contacts, so could be dodgy connection there making electrical interference noise. I would check with ignition on, but engine off, then try the heater see if it's that, then with engine running, but heater/blower off, see if it's ignition related.