Here's my approach to fix the PTT hanging issue of the UV-3R.
Adding a cap at the PTT connector to ground pretty much solved the
problem.
22 pF turned out to be too small,
47 pF still allowed some PTT hanging when holding the antenna close
to the earphone cable,
100 pF finally cured the problem. At least with my UV-3Rs.
There's not much room between the quartz and the connector, so I decided
to use some isolated copper wire and place the capacitor at a small
distance.
The back side of the DC-connector seemed to be a good place to put the
100 pF capacitor.
I didn't have 100 pF in SMD at hand, so I placed two 47 pF in parallel I
had spare from the LPF-mod .
Make sure, the isolated copper wire stays beneath the height of the DCconnector.