PA0O ham radio

I am using this AnyTone 144MHz 10/25/50W FM mobile device last years for local  144MHz traffic. A lot of power from a very small VHF mobile rig  Though it will get very hot in longer chats at the 25 or 50W level The RX-standby power is  0.25A But sometimes it happens that sudden the squelch seem to open and a loud noise comes out. The RX signal level showed 5 bars even with disconnected  antenna. The signal happens to be generated internal. The noise/signal disappears when just touching the power cord or AnyThing(...) external at the device Ghostly ... Found internal a beautiful well build device with gold plated PCB. I have no service document or diagram. Hard to believe that this professional build device would suffer from a self oscillating pre-amp stage, but i can't draw an other conclusion. I could not see any malfunctioning parts.  A wide-band design no tuning parts. Suspect is the first RX FET to have a constant parasitic self-oscillation....