Radio Hash Noise with Dynon Transponder When Turned on

[Bardample]

I have a small problem .Recently I have noticed hash noise in my headphones once the HDX unit is fired up ( before starting engine). After turning lots of switches on and off, checking wires, headsets , grounds etc . I discovered that the Dynon transponder when on ( auto mode prior to take off ) causes the hash noise. When the transponder is turned to Standby, the noise diappears and returns when any mode selected other than Standby is chosen. I checked the Txp ground and antennae connections at aerial and Txp, aswell as wriggling wires etc at rear.

Can any one suggest a reason and has any one else had this issue. Thanks JeffR Australia

 

[PaulSS]

How close is the transponder coax running to the radio cables?