I received an email from Ken Scott. He says the serial number on the AV5000 indicates
it is well outside of the range of problem units. Ken says the whine is not a problem with the control
module.
That is not good news. He also said one of the other techs said it
could be the sidetone on the SL-40. If
the sidetone value is too low the mic will pick-up the engine sound in the
cockpit and cause a whine. I will go to
the airport and try increasing the sidetone on the radio to see if that helps.
