Audi Repair: rev sensitive whirring noise, audi a6, diyer

Question
Audi A6 2.7
There is a whirring sound coming from the car that increases with engine speed. It sounds like interference through the radio, but happens with radio off. Dealer did code check and says there is an open connection in the antenna, but needs more diagnosis (at $99/hr) to figure it out. Can you suggest where a fairly decent DIYer might begin looking?

Answer
Hi
Sorry , that is not easy. Try to disconnect antena from radio, if it goes away there is a diversity box which is getting signal from 4 amps and sents it to radio. Maybe one of the amp or the box itself is shorted inside?
(box is under real shelf on 4 door sedams)
good luck...        PLTECH