At last my UV-3R was subject to the receiver chopping effect that was described on the Yahoo group few months ago.
On the way home I met with a local HAM, then we drove our cars in the same direction, still talking over the usual UHF repeater. Our antennas were 5 to 20 metres apart in the traffic. When he was transmitting on the repeater input frequency, 5 MHz away from my VFO, I could not hear the output signal: I had to switch in reverse (next memory ;-) ) and listen to his direct transmission. My UV-3R was heavily chopping, probably because the receiver was overloaded.
When our paths diverged the reception on the repeater output gradually improved, with the chopping becoming more and more rare.
On the other hand listening to his transmission frequency did not cause any chopping in my receiver. I wonder if other name brands receivers would have behaved differently.
For those interested. I was using the UV-3R with a flexible 19cm dualband antenna on it. The fellow HAM had a V/UHF dualbander with an external antenna at 5W.