After the bad experience with the 30m wire terminated by the MFJ998RT autotuner in order to have a dualband 80/160m antenna, I did a new test : This time I used a 42m wired folded as an inverted L with the highest point at 24m.
Both 80m and 160m can be tuned on this wire. So much better then before.
This doesn't mean the antenna is working fine, but it's allready a better result then last month ! I only use 42m long radials and will keep the 20m radials to connect to my full size 80m wire antenna.
I will certainly switch between the two antennas on 80m during the CW contest..
In the mean time I uninstalled the current balun and 90 degrees PL-connector on the 40m antenna. No traces of smoke nor other failures. Nevertheless I had two sparks so there must have been something wrong.
I don't expect any more sparks followed by amplifier protection and a temporary (strange, why is this occuring only during a few minutes ?!) very bad swr on this Optibeam... I hope...