Hmmm!
The on air tests showed no real improvement in the audio so I think a test of the radio itself is in order. It was working ok, but something may have changed.
And I think the Earthing needs to be fixed up with a couple of ground stakes.
On the SA SDR, I did see some bursts of really strong signal so there may be a crook connection there.
When they restock, I'll change the UnUn from...
to the proven Jaycar cores ....