Several TS-480 users on Yahoo Groups have reported RF in the mic problems when using other than the stock mic.
It appears Kenwood is aware that the 480 ground pins are wired differently than their other radios. This, notwithstanding the fact that the TS-480 user manual indicates they are wired the same (see page 80).
The following appeared Fri Mar 11, 2005 on the Yahoo Group as an e-mail reply from Kenwood regarding this issue:
[Begin Kenwood E-mail Quote]
Dear Kenwood Customer:
This information pertains to the TS-480SAT/ TS-480HX RJ-45 Microphone Connections. Pin 3 of Microphone Connector is Microphone Ground, and Pin 5 is System Ground.
Other Kenwood mobile radio's, Pin 3 is System Ground, and Pin 5 is Microphone Ground. That information is on page 80 in the TS-480 instruction manual center diagram on the TS-480 side.
If you need further assistance, please e-mail us again.
Kenwood Amateur Radio Customer Support
[End Kenwood E-mail Quote]
So, reversing the Pin 3 and Pin 5 Ground Connections using a short length custom wired RJ-45 Jumper is an easy method of correcting this grounds issue without cutting any of your existing non stock mic connections.
Some have prefered to simply cut, rewire, and replace the RJ-45 connection on the Kenwood MJ-88 8 Pin round to Modular RJ-45 adapter cable.
This has solved the RF in the mic problems for many who prefer to use other than the stock mic sold with the rig.
Hope this helps.