Hi Juha,
One site I found helpful for this project is here:
https://ke4rg.blogspot.com/2015/03/assembling-and-using-kpa100kat100-ec2.htmlThe EC2 enclosure is a "retired product" at Elecraft - no longer available from them.
I may have purchased the very last EC2 in stock back in 2018 if I recall my
phone conversation with Madeline - that's when I built and integrated the
100 watt amp and ATU.
Perhaps there are some unused EC2 enclosures out there among
the readers of this reflector.
73,
Mike, K8CN