Dear all,

The flange of the STX/F12/F15 waveguide is 113,5mm out diameter, pretty close to 4,5".

There are two set of bolt circles:
For the D2 with 70mm diameter and two bolt holes
For the 2450SL, 243X, 2453 aso with 82,5mm and with 4 bolt holes.

The bigger bolt circle for the 2451 is half of the hole outside the WG. That iswhy I did adapter plates described above. I could not get another mount strongenough to hold the driver hanging and keep centered over time.

In my adapter drawing the thickness of the adapter is alittle less that 1mm which seem to work fine. Originally I had a thicker platebut that was not as good when measured with 2451/475Nd drivers. A 6-10mmdistance was clearly measurable as an un-even curve.
Pictures will follow soon

Kind regards
//Robert