UHF static when transmitting

[Nev62]

My aging Philips UHF radio receives and transmits fine with the engine turned off or at idle. When driving along it still receives find but when I transmit, all anyone hears is a nice clear loud distortion. Put my foot on the clutch, let the reves come down to idle and all is ok again.

Could this be caused by a poor engine earth or would a line filter on the power supply line fix the problem? Aerial and coax is good. The radio has a plastic case so I cannot earth it out.

[dumbdunce]

there is a steel case inside the plastic case that should be earthed by the negative power terminal and the antenna shield. start by testing the antenna shield for continuity to the chassis (and earthing of the engine, alternator etc as you have suggested). and also leakage between the antenna shielding and the core.

its definitely an earthing and/or shielding problem. does the antenna cable run anywhere near the alternator, distributor/coil packs, high tension leads etc?

[Nev62]

its definitely an earthing and/or shielding problem. does the antenna cable run anywhere near the alternator, distributor/coil packs, high tension leads etc?

Nah, I've kept it right away from them. I'll have another look at contanuity and possible leakage between the inner core and shielding at the plug (which I put on). I've also had the case apart and there is no inner shield, just a plastic case