Latest video, this one is on the Collins HF-80 receiver, big box with lots of engineering. Maybe Collins idea as a answer to a SSB/ISB version of R-390? Can run up to four channels of side band at once. Also they did lock everything to a common reference so far better in terms of phase noise and stability to any of there tube products. Thinner then the R-390 but longer and appears to be almost as heavy! And just like the R-390 or 390A still a chore to tune.

https://www.youtube.com/watch?v=GVwQfLN_pbQ

Ray F/KA3EKH