Thank you, David, for taking the time to study this.
As Arv referred me to the HBTE forum, I think there are more "contentporary" examples than this one which dates back to 2010.
I will look closely to see if there is a complete project.
My request is not very demanding a spectral analyzer up to 300 MHZ is enough for me. (With possibility tracking for tsting filters)
cdt
Gerard