When I transmit with a MD-380 and a rubber-duck antenna, there is a "motorboat" sound on my transmit audio when using a Retelvis speaker mic. I opened the mic and observed that they are not using a shielded mic cable. When I transmit into a dummy load or an outside antenna the "motorboat" sound is gone.
Has anyone been able to fix this RF into audio problem and what speaker microphones do not have this problem?
The problem goes away when you use the proper mic for it... such as the following unit.