[R-390] R390 PTO endpoint

[jgedde at optonline.net]

I've started to look into doing the PTO endpoint on my R390.  The PTO is
completely different than the Cosmos one on my R390A which I was successful
in calibrating, including linearity.  Where is the endpoint adjustment on
the Collins R390 PTO?  I can barely see a plug behind the transformer can.
Is that where it's hiding?  

 

My PTO also has a plastic plug screwed into a hole marked S701.  Behind the
plug is a hollow shaft with two notches to allow it to be turned with a
screwdriver.  What is that for?  It does nothing as far as varying the
frequency.

 

There is so much wealth of information online about the R390A and its
various PTO flavors, but not much about the R390 PTO.

 

73's,

John