Hello Werner,
A while ago, I worked with the Calbe R09. The datasheet for the R09 can be found here:
http://www.calbe-chemie.de/shop/pdf/R%2009.pdf
I developed a few APX100 films in R09 as a test. I used a dilution of 1+50 and developed them for 17 minutes. The film was exposed as ISO 64/19. Perhaps this is a suitable starting point for your own tests.
Best regards,
Otto Beyer!